mk: Fix NO_REBUILD so stdtest can be tested without re-bootstrapping. Closes #8101
mk: Rename CTEST_BENCH to TEST_BENCH

The CTEST prefix is specifically related to the compiletest driver
mk: Add NO_BENCH variable for turning off the --bench flag
Remove ChanOneHack/PortOneHack extra allocation
Optimize try_recv to not require the two context switches when data is available.
Add some missing method wrappers to std::num
Improve std::num module description, and fix some formatting
implement pointer arithmetic with GEP

Closes #8118, #7136

~~~rust
extern mod extra;

use std::vec;
use std::ptr;

fn bench_from_elem(b: &mut extra::test::BenchHarness) {
    do b.iter {
        let v: ~[u8] = vec::from_elem(1024, 0u8);
    }
}

fn bench_set_memory(b: &mut extra::test::BenchHarness) {
    do b.iter {
        let mut v: ~[u8] = vec::with_capacity(1024);
        unsafe {
            let vp = vec::raw::to_mut_ptr(v);
            ptr::set_memory(vp, 0, 1024);
            vec::raw::set_len(&mut v, 1024);
        }
    }
}

fn bench_vec_repeat(b: &mut extra::test::BenchHarness) {
    do b.iter {
        let v: ~[u8] = ~[0u8, ..1024];
    }
}
~~~

Before:

    test bench_from_elem ... bench: 415 ns/iter (+/- 17)
    test bench_set_memory ... bench: 85 ns/iter (+/- 4)
    test bench_vec_repeat ... bench: 83 ns/iter (+/- 3)

After:

    test bench_from_elem ... bench: 84 ns/iter (+/- 2)
    test bench_set_memory ... bench: 84 ns/iter (+/- 5)
    test bench_vec_repeat ... bench: 84 ns/iter (+/- 3)
auto merge of #8110 : brson/rust/no-rebuild, r=bblum

...oses #8101
auto merge of #8082 : Kimundi/rust/master, r=huonw

Also renamed bytes_iter to byte_iter to match other iterators
auto merge of #8121 : thestinger/rust/offset, r=alexcrichton

Closes #8118, #7136

~~~rust
extern mod extra;

use std::vec;
use std::ptr;

fn bench_from_elem(b: &mut extra::test::BenchHarness) {
    do b.iter {
        let v: ~[u8] = vec::from_elem(1024, 0u8);
    }
}

fn bench_set_memory(b: &mut extra::test::BenchHarness) {
    do b.iter {
        let mut v: ~[u8] = vec::with_capacity(1024);
        unsafe {
            let vp = vec::raw::to_mut_ptr(v);
            ptr::set_memory(vp, 0, 1024);
            vec::raw::set_len(&mut v, 1024);
        }
    }
}

fn bench_vec_repeat(b: &mut extra::test::BenchHarness) {
    do b.iter {
        let v: ~[u8] = ~[0u8, ..1024];
    }
}
~~~

Before:

    test bench_from_elem ... bench: 415 ns/iter (+/- 17)
    test bench_set_memory ... bench: 85 ns/iter (+/- 4)
    test bench_vec_repeat ... bench: 83 ns/iter (+/- 3)

After:

    test bench_from_elem ... bench: 84 ns/iter (+/- 2)
    test bench_set_memory ... bench: 84 ns/iter (+/- 5)
    test bench_vec_repeat ... bench: 84 ns/iter (+/- 3)
std: Disallow bytes 0xC0, 0xC1 (192, 193) in utf-8

Bytes 0xC0, 0xC1 can only be used to start 2-byte codepoint encodings,
that are 'overlong encodings' of codepoints below 128.

The reference given in a comment -- https://tools.ietf.org/html/rfc3629
-- does in fact already exclude these bytes, so no additional comment
should be needed in the code.
Do not enforce two newlines after the options
std: Deny overlong encodings in UTF-8

An 'overlong encoding' is a codepoint encoded non-minimally using the
utf-8 format. Denying these enforce each codepoint to have only one
valid representation in utf-8.

An example is byte sequence 0xE0 0x80 0x80 which could be interpreted as
U+0, but it's an overlong encoding since the canonical form is just
0x00.

Another example is 0xE0 0x80 0xAF which was previously accepted and is
an overlong encoding of the solidus "/". Directory traversal characters
like / and . form the most compelling argument for why this commit is
security critical.

Factor out common UTF-8 decoding expressions as macros. This commit will
partly duplicate UTF-8 decoding, so it is now present in both
fn is_utf8() and .char_range_at(); the latter using an assumption of
a valid str.
std: Add from_bytes test for utf-8 using codepoints above 0xffff
Implement select() for new runtime pipes.
Add test cases for select
Add a better-for-testing optimistic_check() for pipes with cfg(test).
(cleanup) Fix unimplemented message for kill_all in newsched.
Unkillable is not unsafe. Close #7832.