complete btree rewrite

Replaces BTree with BTreeMap and BTreeSet, which are completely new implementations.
BTreeMap's internal Node representation is particularly inefficient at the moment to
make this first implementation easy to reason about and fairly safe. Both collections
are also currently missing some of the tooling specific to sorted collections, which
is planned as future work pending reform of these APIs. General implementation issues
are discussed with TODOs internally

Perf results on x86_64 Linux:

test treemap::bench::find_rand_100                         ... bench:        76 ns/iter (+/- 4)
test treemap::bench::find_rand_10_000                      ... bench:       163 ns/iter (+/- 6)
test treemap::bench::find_seq_100                          ... bench:        77 ns/iter (+/- 3)
test treemap::bench::find_seq_10_000                       ... bench:       115 ns/iter (+/- 1)
test treemap::bench::insert_rand_100                       ... bench:       111 ns/iter (+/- 1)
test treemap::bench::insert_rand_10_000                    ... bench:       996 ns/iter (+/- 18)
test treemap::bench::insert_seq_100                        ... bench:       486 ns/iter (+/- 20)
test treemap::bench::insert_seq_10_000                     ... bench:       800 ns/iter (+/- 15)

test btree::map::bench::find_rand_100                      ... bench:        74 ns/iter (+/- 4)
test btree::map::bench::find_rand_10_000                   ... bench:       153 ns/iter (+/- 5)
test btree::map::bench::find_seq_100                       ... bench:        82 ns/iter (+/- 1)
test btree::map::bench::find_seq_10_000                    ... bench:       108 ns/iter (+/- 0)
test btree::map::bench::insert_rand_100                    ... bench:       220 ns/iter (+/- 1)
test btree::map::bench::insert_rand_10_000                 ... bench:       620 ns/iter (+/- 16)
test btree::map::bench::insert_seq_100                     ... bench:       411 ns/iter (+/- 12)
test btree::map::bench::insert_seq_10_000                  ... bench:       534 ns/iter (+/- 14)

BTreeMap still has a lot of room for optimization, but it's already beating out TreeMap on most access patterns.

[breaking-change]
auto merge of #17334 : Gankro/rust/btree-vec, r=huonw

Replaces BTree with BTreeMap and BTreeSet, which are completely new implementations.
BTreeMap's internal Node representation is particularly inefficient at the moment to
make this first implementation easy to reason about and fairly safe. Both collections
are also currently missing some of the tooling specific to sorted collections, which
is planned as future work pending reform of these APIs. General implementation issues
are discussed with TODOs internally

[breaking-change]

Still waiting on compilation/test/bench stuff locally, but the edit-distance on any errors should be very small at this point. This is ready to be reviewed.
Translate inline assembly errors back to source locations

Fixes #17552.
auto merge of #17517 : pczarn/rust/hashmap-lifetimes, r=alexcrichton

Fixes #17500
make EnumSet derive Ord and PartialOrd
auto merge of #17523 : TeXitoi/rust/relicense-shootout-fasta-redux, r=brson

Everyone agreed.

Fix #17078 

#14248 seems completed, as every src/test/bench/shootout-*.rs are relicensed after acceptation of this PR except:
- shootout-ackermann.rs: obsolete shootout bench
- shootout-fibo.rs:  obsolete shootout bench
- shootout-k-nucleotide-pipes.rs: slower that shootout-k-nucleotide-pipes.rs (and not so interesting as a benchmark)
- shootout-pfib.rs: does not seems related to the shootout

@brson OK?
Defailbloat fail!(&'static str)
auto merge of #17529 : nodakai/rust/rustdoc-div-in-h1, r=alexcrichton

W3C HTML5 spec states that H1 must enclose "phrasing content" which
doesn't include DIV.  But SPAN is OK.
http://www.w3.org/TR/html5/sections.html#the-h1,-h2,-h3,-h4,-h5,-and-h6-elements
Convert cfg syntax to new system

This removes the ability to use `foo(bar)` style cfgs. Switch them to
`foo_bar` or `foo="bar"` instead.

[breaking-change]
auto merge of #17527 : sfackler/rust/cfg-syntax, r=alexcrichton

We'll need a snapshot before we can convert the codebase over and turn on the deprecation warnings.

cc #17490

This is sitting on top of #17506
auto merge of #17532 : ahmedcharles/rust/typo, r=alexcrichton
Keep ExpnId abstract by providing conversions
Cleanup error messages for anonymous impl for types not declared in the current module

Followup to RFC 57.

Fixes #7607
Fixes #8767
Fixes #12729
Fixes #15060
Correctly populate trait impl map when checking for impl overlaps

Also fix an existing compile-fail test which was intended to cover
this case.

This closes issue #17593
Test for `..` in range patterns
Reject casts to unsized types and suggest use of reference or box

This prevents ICEs or less helpful diagnostics if typeck proceeds
further.  Closes issue #17441
Add regression test for issue #17441
auto merge of #17533 : michaelwoerister/rust/function-call-locs, r=luqmana

This PR makes rustc emit debug locations for *all* call and invoke statements in LLVM IR, if they are contained within a function that debuginfo is enabled for. This is important because LLVM does not handle the case where a function body containing debuginfo is inlined into another function with debuginfo, but the inlined call statement does not have a debug location. In this case, LLVM will not know where (in terms of source code coordinates) the function was inlined to and we end up with some statements still linked to the source locations in there original, non-inlined function without any indication that they are indeed an inline-copy. Later, when generating DWARF from the IR, LLVM will interpret this as corrupt IR and abort.

Unfortunately, the undesirable case described above can still occur when using LTO. If there is a crate compiled without debuginfo calling into a crate compiled with debuginfo, we again end up with the conditions triggering the error. This is why some LTO tests still fail with the dreaded assertion, if the standard library was built with debuginfo enabled. That is, `RUSTFLAGS_STAGE2=-g make rustc-stage2` will succeed but `RUSTFLAGS_STAGE2=-g make check` will still fail after this PR has been merged. I will open a separate issue for this problem.
Register new snapshots
Use the same JSON schema for encoding enums in PrettyEncoder as in Encoder

Closes issue #17607