Make most of the failure functions take &(&'static str, uint)

Passing one pointer takes less code than one pointer and an integer.
Put the struct passed to unwinding functions into a static

Produces very clean asm, but makes bigger binaries.
core: Remove unneeded cfgs
std: Use correct conventions for statics in macros
Revert "Use fewer instructions for `fail!`"

This reverts commit c61f9763e2e03afbe62445877ceb3ed15e22e123.

Conflicts:
	src/librustrt/unwind.rs
	src/libstd/macros.rs
Remove an unneeded FIXME in coherence.rs

Also, let f; f = ...; is just wrong.
auto merge of #16031 : arielb1/rust/remove_unneeded_fixme, r=kballard

The issue was fixed a month ago - remove the workaround.
rustdoc: show struct field docs when inlined

Some minor changes to the compiler to expose this information. Very
inconvenient since struct fields aren't an item. Adds (yet another) table to
metadata.

Closes #15739
rustdoc: remove extraneous .move_iter().collect()s

The impl of Clean for Vec obsoleted these long, long ago.
rustc: encode is_sugared_doc on ast::Attribute
doc: Method examples for String

Reword comments on unsafe methods regarding UTF-8.
auto merge of #16025 : cmr/rust/plugin-fields, r=alexcrichton

Some minor changes to the compiler to expose this information. Very
inconvenient since struct fields aren't an item.
Use correct conventions for static
auto merge of #15983 : brson/rust/fail, r=alexcrichton

A few refactorings to decrease text size and increase data size. I'm not sure about this tradeoff. Various stats below. cc @pcwalton

This reduces the code needed to pass arguments for `fail!()`, `fail!("{}", ...)`, and to a lesser extent `fail!("...")`. Still more work to be done on compiler-generated failures and the `fail!("...")` case.

do_fail_empty:

```
#[inline(never)]
fn do_fail_empty() {
    fail!()
}
```

do_fail_empty before:

```
	leaq	8(%rsp), %rdi
	movabsq	$13, %rsi
	leaq	"str\"str\"(1494)"(%rip), %rax
	movq	%rax, 8(%rsp)
	movq	$19, 16(%rsp)
	callq	_ZN6unwind31begin_unwind_no_time_to_explain20h57030457935ab6111SdE@PLT
```

do_fail_empty after:

```
	leaq	_ZN13do_fail_empty9file_line20h339df6a0541e837eIaaE(%rip), %rdi
	callq	_ZN6unwind31begin_unwind_no_time_to_explain20h33184cfdcce4dfd8QTdE@PLT
```

do_fail_fmt:

```
#[inline(never)]
fn do_fail_fmt() {
    fail!("guh{}", "faw")
}
```

do_fail_fmt before:

```
        ... (snip lots of fmt stuff)
	callq	_ZN3fmt22Arguments$LT$$x27a$GT$3new20he09b3a3f473879c41paE
	leaq	144(%rsp), %rsi
	movabsq	$23, %rdx
	leaq	"str\"str\"(1494)"(%rip), %rax
	leaq	32(%rsp), %rcx
	movq	%rcx, 160(%rsp)
	movq	160(%rsp), %rdi
	movq	%rax, 144(%rsp)
	movq	$19, 152(%rsp)
	callq	_ZN6unwind16begin_unwind_fmt20h3ebeb42f4d189b2buQdE@PLT
```

do_fail_fmt after:

```
        ... (snip lots of fmt stuff)
	callq	_ZN3fmt22Arguments$LT$$x27a$GT$3new20h42e5bb8d1711ee61OqaE
	leaq	_ZN11do_fail_fmt7run_fmt9file_line20h339df6a0541e837eFbaE(%rip), %rsi
	leaq	32(%rsp), %rax
	movq	%rax, 144(%rsp)
	movq	144(%rsp), %rdi
	callq	_ZN6unwind16begin_unwind_fmt20hfdcadc14d188656biRdE@PLT
```

File size increases.

file size before:

```
-rw-rw-r-- 1 brian brian 100501740 Jul 24 23:28 /home/brian/dev/rust2/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc-4e7c5e5c.rlib
-rwxrwxr-x 1 brian brian  21201780 Jul 24 23:27 /home/brian/dev/rust2/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc-4e7c5e5c.so
```

file size after:

```
-rw-rw-r-- 1 brian brian 101542484 Jul 25 00:34 x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc-4e7c5e5c.rlib
-rwxrwxr-x 1 brian brian  21348862 Jul 25 00:34 x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc-4e7c5e5c.so
```

Text size decreases by 52486 while data size increases by 143686.

section size before:

```
   text    data     bss     dec     hex filename
12712262        5924997     368 18637627        11c633b x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc-4e7c5e5c.so
```

section size after:

```
   text    data     bss     dec     hex filename
12659776        6068683     368 18728827        11dc77b /home/brian/dev/rust/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc-4e7c5e5c.so
```

I don't know if anything can be learned from these benchmarks. Looks like a wash.

std bench before:

```
test collections::hashmap::bench::find_existing             ... bench:     43452 ns/iter (+/- 2423)
test collections::hashmap::bench::find_nonexisting          ... bench:     42416 ns/iter (+/- 3996)
test collections::hashmap::bench::find_pop_insert           ... bench:       214 ns/iter (+/- 11)
test collections::hashmap::bench::hashmap_as_queue          ... bench:       123 ns/iter (+/- 6)
test collections::hashmap::bench::insert                    ... bench:       153 ns/iter (+/- 14)
test collections::hashmap::bench::new_drop                  ... bench:       547 ns/iter (+/- 259)
test collections::hashmap::bench::new_insert_drop           ... bench:       682 ns/iter (+/- 366)
test io::buffered::test::bench_buffered_reader              ... bench:      1046 ns/iter (+/- 86)
test io::buffered::test::bench_buffered_stream              ... bench:      2156 ns/iter (+/- 801)
test io::buffered::test::bench_buffered_writer              ... bench:      1057 ns/iter (+/- 75)
test io::extensions::bench::u64_from_be_bytes_4_aligned     ... bench:        80 ns/iter (+/- 5)
test io::extensions::bench::u64_from_be_bytes_4_unaligned   ... bench:        81 ns/iter (+/- 6)
test io::extensions::bench::u64_from_be_bytes_7_aligned     ... bench:        80 ns/iter (+/- 4)
test io::extensions::bench::u64_from_be_bytes_7_unaligned   ... bench:        69 ns/iter (+/- 4)
test io::extensions::bench::u64_from_be_bytes_8_aligned     ... bench:        69 ns/iter (+/- 3)
test io::extensions::bench::u64_from_be_bytes_8_unaligned   ... bench:        81 ns/iter (+/- 4)
test io::mem::test::bench_buf_reader                        ... bench:       628 ns/iter (+/- 18)
test io::mem::test::bench_buf_writer                        ... bench:       478 ns/iter (+/- 19)
test io::mem::test::bench_mem_reader                        ... bench:       712 ns/iter (+/- 44)
test io::mem::test::bench_mem_writer_001_0000               ... bench:        31 ns/iter (+/- 1)
test io::mem::test::bench_mem_writer_001_0010               ... bench:        51 ns/iter (+/- 3)
test io::mem::test::bench_mem_writer_001_0100               ... bench:       121 ns/iter (+/- 8)
test io::mem::test::bench_mem_writer_001_1000               ... bench:       774 ns/iter (+/- 47)
test io::mem::test::bench_mem_writer_100_0000               ... bench:       756 ns/iter (+/- 50)
test io::mem::test::bench_mem_writer_100_0010               ... bench:      2726 ns/iter (+/- 198)
test io::mem::test::bench_mem_writer_100_0100               ... bench:      8961 ns/iter (+/- 712)
test io::mem::test::bench_mem_writer_100_1000               ... bench:    105673 ns/iter (+/- 24711)
test num::bench::bench_pow_function                         ... bench:      5849 ns/iter (+/- 371)
test num::strconv::bench::f64::float_to_string              ... bench:       662 ns/iter (+/- 202)
test num::strconv::bench::int::to_str_base_36               ... bench:       424 ns/iter (+/- 7)
test num::strconv::bench::int::to_str_bin                   ... bench:      1227 ns/iter (+/- 80)
test num::strconv::bench::int::to_str_dec                   ... bench:       466 ns/iter (+/- 13)
test num::strconv::bench::int::to_str_hex                   ... bench:       498 ns/iter (+/- 22)
test num::strconv::bench::int::to_str_oct                   ... bench:       502 ns/iter (+/- 229)
test num::strconv::bench::uint::to_str_base_36              ... bench:       375 ns/iter (+/- 7)
test num::strconv::bench::uint::to_str_bin                  ... bench:      1011 ns/iter (+/- 590)
test num::strconv::bench::uint::to_str_dec                  ... bench:       407 ns/iter (+/- 17)
test num::strconv::bench::uint::to_str_hex                  ... bench:       442 ns/iter (+/- 7)
test num::strconv::bench::uint::to_str_oct                  ... bench:       433 ns/iter (+/- 46)
test path::posix::bench::ends_with_path_home_dir            ... bench:       167 ns/iter (+/- 10)
test path::posix::bench::ends_with_path_missmatch_jome_home ... bench:       148 ns/iter (+/- 6)
test path::posix::bench::is_ancestor_of_path_with_10_dirs   ... bench:       221 ns/iter (+/- 31)
test path::posix::bench::join_abs_path_home_dir             ... bench:       144 ns/iter (+/- 23)
test path::posix::bench::join_home_dir                      ... bench:       196 ns/iter (+/- 9)
test path::posix::bench::join_many_abs_path_home_dir        ... bench:       143 ns/iter (+/- 6)
test path::posix::bench::join_many_home_dir                 ... bench:       195 ns/iter (+/- 8)
test path::posix::bench::path_relative_from_backward        ... bench:       248 ns/iter (+/- 10)
test path::posix::bench::path_relative_from_forward         ... bench:       241 ns/iter (+/- 13)
test path::posix::bench::path_relative_from_same_level      ... bench:       296 ns/iter (+/- 11)
test path::posix::bench::push_abs_path_home_dir             ... bench:       104 ns/iter (+/- 7)
test path::posix::bench::push_home_dir                      ... bench:     27311 ns/iter (+/- 2727)
test path::posix::bench::push_many_abs_path_home_dir        ... bench:       109 ns/iter (+/- 5)
test path::posix::bench::push_many_home_dir                 ... bench:     23263 ns/iter (+/- 1726)
test rand::bench::rand_isaac                                ... bench:       884 ns/iter (+/- 31) = 904 MB/s
test rand::bench::rand_isaac64                              ... bench:       440 ns/iter (+/- 126) = 1818 MB/s
test rand::bench::rand_shuffle_100                          ... bench:      2518 ns/iter (+/- 1371)
test rand::bench::rand_std                                  ... bench:       429 ns/iter (+/- 17) = 1864 MB/s
test rand::bench::rand_xorshift                             ... bench:         0 ns/iter (+/- 0) = 800000 MB/s
```

std bench after:

```
test collections::hashmap::bench::find_existing             ... bench:     43635 ns/iter (+/- 4508)
test collections::hashmap::bench::find_nonexisting          ... bench:     42323 ns/iter (+/- 1753)
test collections::hashmap::bench::find_pop_insert           ... bench:       216 ns/iter (+/- 11)
test collections::hashmap::bench::hashmap_as_queue          ... bench:       125 ns/iter (+/- 8)
test collections::hashmap::bench::insert                    ... bench:       153 ns/iter (+/- 63)
test collections::hashmap::bench::new_drop                  ... bench:       517 ns/iter (+/- 282)
test collections::hashmap::bench::new_insert_drop           ... bench:       734 ns/iter (+/- 264)
test io::buffered::test::bench_buffered_reader              ... bench:      1063 ns/iter (+/- 206)
test io::buffered::test::bench_buffered_stream              ... bench:      2321 ns/iter (+/- 2302)
test io::buffered::test::bench_buffered_writer              ... bench:      1060 ns/iter (+/- 24)
test io::extensions::bench::u64_from_be_bytes_4_aligned     ... bench:        69 ns/iter (+/- 2)
test io::extensions::bench::u64_from_be_bytes_4_unaligned   ... bench:        81 ns/iter (+/- 7)
test io::extensions::bench::u64_from_be_bytes_7_aligned     ... bench:        70 ns/iter (+/- 5)
test io::extensions::bench::u64_from_be_bytes_7_unaligned   ... bench:        69 ns/iter (+/- 5)
test io::extensions::bench::u64_from_be_bytes_8_aligned     ... bench:        80 ns/iter (+/- 6)
test io::extensions::bench::u64_from_be_bytes_8_unaligned   ... bench:        81 ns/iter (+/- 5)
test io::mem::test::bench_buf_reader                        ... bench:       663 ns/iter (+/- 44)
test io::mem::test::bench_buf_writer                        ... bench:       489 ns/iter (+/- 17)
test io::mem::test::bench_mem_reader                        ... bench:       700 ns/iter (+/- 23)
test io::mem::test::bench_mem_writer_001_0000               ... bench:        31 ns/iter (+/- 3)
test io::mem::test::bench_mem_writer_001_0010               ... bench:        49 ns/iter (+/- 5)
test io::mem::test::bench_mem_writer_001_0100               ... bench:       112 ns/iter (+/- 6)
test io::mem::test::bench_mem_writer_001_1000               ... bench:       765 ns/iter (+/- 59)
test io::mem::test::bench_mem_writer_100_0000               ... bench:       727 ns/iter (+/- 54)
test io::mem::test::bench_mem_writer_100_0010               ... bench:      2586 ns/iter (+/- 215)
test io::mem::test::bench_mem_writer_100_0100               ... bench:      8846 ns/iter (+/- 439)
test io::mem::test::bench_mem_writer_100_1000               ... bench:    105747 ns/iter (+/- 17443)
test num::bench::bench_pow_function                         ... bench:      5844 ns/iter (+/- 421)
test num::strconv::bench::f64::float_to_string              ... bench:       669 ns/iter (+/- 571)
test num::strconv::bench::int::to_str_base_36               ... bench:       417 ns/iter (+/- 24)
test num::strconv::bench::int::to_str_bin                   ... bench:      1216 ns/iter (+/- 36)
test num::strconv::bench::int::to_str_dec                   ... bench:       466 ns/iter (+/- 24)
test num::strconv::bench::int::to_str_hex                   ... bench:       492 ns/iter (+/- 8)
test num::strconv::bench::int::to_str_oct                   ... bench:       496 ns/iter (+/- 295)
test num::strconv::bench::uint::to_str_base_36              ... bench:       366 ns/iter (+/- 8)
test num::strconv::bench::uint::to_str_bin                  ... bench:      1005 ns/iter (+/- 69)
test num::strconv::bench::uint::to_str_dec                  ... bench:       396 ns/iter (+/- 20)
test num::strconv::bench::uint::to_str_hex                  ... bench:       435 ns/iter (+/- 4)
test num::strconv::bench::uint::to_str_oct                  ... bench:       436 ns/iter (+/- 451)
test path::posix::bench::ends_with_path_home_dir            ... bench:       171 ns/iter (+/- 6)
test path::posix::bench::ends_with_path_missmatch_jome_home ... bench:       152 ns/iter (+/- 6)
test path::posix::bench::is_ancestor_of_path_with_10_dirs   ... bench:       215 ns/iter (+/- 8)
test path::posix::bench::join_abs_path_home_dir             ... bench:       143 ns/iter (+/- 6)
test path::posix::bench::join_home_dir                      ... bench:       192 ns/iter (+/- 29)
test path::posix::bench::join_many_abs_path_home_dir        ... bench:       144 ns/iter (+/- 9)
test path::posix::bench::join_many_home_dir                 ... bench:       194 ns/iter (+/- 19)
test path::posix::bench::path_relative_from_backward        ... bench:       254 ns/iter (+/- 15)
test path::posix::bench::path_relative_from_forward         ... bench:       244 ns/iter (+/- 17)
test path::posix::bench::path_relative_from_same_level      ... bench:       293 ns/iter (+/- 27)
test path::posix::bench::push_abs_path_home_dir             ... bench:       108 ns/iter (+/- 5)
test path::posix::bench::push_home_dir                      ... bench:     32292 ns/iter (+/- 4361)
test path::posix::bench::push_many_abs_path_home_dir        ... bench:       108 ns/iter (+/- 6)
test path::posix::bench::push_many_home_dir                 ... bench:     20305 ns/iter (+/- 1331)
test rand::bench::rand_isaac                                ... bench:       888 ns/iter (+/- 35) = 900 MB/s
test rand::bench::rand_isaac64                              ... bench:       439 ns/iter (+/- 17) = 1822 MB/s
test rand::bench::rand_shuffle_100                          ... bench:      2582 ns/iter (+/- 1001)
test rand::bench::rand_std                                  ... bench:       431 ns/iter (+/- 93) = 1856 MB/s
test rand::bench::rand_xorshift                             ... bench:         0 ns/iter (+/- 0) = 800000 MB/s
```
auto merge of #16027 : treeman/rust/doc-string, r=alexcrichton
syntax: add some more extension helper methods
syntax: allow quasiquoter to inline `Vec<Stmt>`s
syntax: promote a comment on PatEnum into a docstring
Fix a bug pretty printing `match { 5i } { _ => { } }`

This also always puts a trailing comma on the last non-block expr.
syntax: add support for quoting arms