rustc: Fix support for LLVM 3.3

The llvm.copysign and llvm.round intrinsics weren't added until LLVM 3.4, so if
we're on LLVM 3.3 we lower these to calls in libm instead of LLVM intrinsics.

This should fix our travis failures.
travis: Use LLVM 3.4 instead of LLVM 3.3

This version is slightly more up to date and is closer to the 3.5 that we're
using. This also updates the travis config to have a build matrix which tests
rust against LLVM 3.3 and 3.4. For pull requests only LLVM 3.4 is tested to
reduce the load on travis.

This is mostly just fluff, there's no real reason to gate rust on these results,
it's more of just a nice thing to know when we break compatibility with LLVM 3.3
and 3.4 (and eventually 3.5). This turns off notifications of failed commits
(which are sent out for pushes to master).
auto merge of #12719 : alexcrichton/rust/fix-llvm-33, r=brson

The llvm.copysign and llvm.round intrinsics weren't added until LLVM 3.4, so if
we're on LLVM 3.3 we lower these to calls in libm instead of LLVM intrinsics.

This should fix our travis failures.
fix typos with with repeated words, just like this sentence.
auto merge of #12726 : alexcrichton/rust/travis, r=brson

This version is slightly more up to date and is closer to the 3.5 that we're
using. This also updates the travis config to have a build matrix which tests
rust against LLVM 3.3 and 3.4. For pull requests only LLVM 3.4 is tested to
reduce the load on travis.

This is mostly just fluff, there's no real reason to gate rust on these results,
it's more of just a nice thing to know when we break compatibility with LLVM 3.3
and 3.4 (and eventually 3.5). This turns off notifications of failed commits
(which are sent out for pushes to master).
auto merge of #12727 : lifthrasiir/rust/buffalo-buffalo, r=huonw

Cosmetic changes at best, but there are so many such typos that I couldn't ignore them. :) Some occurrences of typos are linked to the generated documentations but no changes should break the builds.
rustc: Get LLVM error message safely

On Windows, `LLVMRustGetLastError()` may return non-utf8 mojibake string
if system uses non-English locale. It caused ICE when llvm fails.
This patch doesn't fix the real problem, but just make rustc not die.
Added missing possessive apostrophe.
rustdoc: Don't escape contents of headers

Turns out sundown has already escaped this content for us, so there's no need
for us to escape it again.

Closes #12736
auto merge of #12720 : iliekturtles/rust/master, r=alexcrichton
test: Add some tests for closed issues

Closes #6738
Closes #7061
Closes #7899
Closes #9719
Closes #10028
Closes #10228
Closes #10401
Closes #11192
Closes #11508
Closes #11529
Closes #11873
Closes #11925
auto merge of #12732 : klutzy/rust/this-is-windows, r=alexcrichton

On Windows, `LLVMRustGetLastError()` may return non-utf8 mojibake string
if system uses non-English locale. It caused ICE when llvm fails.
This patch doesn't fix the real problem, but just make rustc not die.
auto merge of #12737 : alexcrichton/rust/issue-12736, r=brson

Turns out sundown has already escaped this content for us, so there's no need
for us to escape it again.

Closes #12736
auto merge of #12738 : alexcrichton/rust/needstest, r=brson,just

Closes #6738
Closes #7061
Closes #7899
Closes #9719
Closes #10028
Closes #10228
Closes #10401
Closes #11192
Closes #11508
Closes #11529
Closes #11873
Closes #11925
rustc: Move to FNV hashing for node/def ids

This leverages the new hashing framework and hashmap implementation to provide a
much speedier hashing algorithm for node ids and def ids. The hash algorithm
used is currentl FNV hashing, but it's quite easy to swap out.

I originally implemented hashing as the identity function, but this actually
ended up in slowing down rustc compiling libstd from 8s to 13s. I would suspect
that this is a result of a large number of collisions.

With FNV hashing, we get these timings (compiling with --no-trans, in seconds):

|           |  before  |  after  |
|-----------|---------:|--------:|
| libstd    |   8.324  |  6.703  |
| stdtest   |  47.674  | 46.857  |
| libsyntax |   9.918  |  8.400  |
collections: Correct with_capacity_and_hasher

The arguments were accidentally swapped in the wrong order.

Closes #12743
syntax: Conditionally deriving(Hash) with Writers

If #[feature(default_type_parameters)] is enabled for a crate, then
deriving(Hash) will expand with Hash<W: Writer> instead of Hash<SipState> so
more hash algorithms can be used.
auto merge of #12635 : alexcrichton/rust/speedy-hash, r=brson

This leverages the new hashing framework and hashmap implementation to provide a
much speedier hashing algorithm for node ids and def ids. The hash algorithm
used is currentl FNV hashing, but it's quite easy to swap out.

I originally implemented hashing as the identity function, but this actually
ended up in slowing down rustc compiling libstd from 8s to 13s. I would suspect
that this is a result of a large number of collisions.

With FNV hashing, we get these timings (compiling with --no-trans, in seconds):

|           |  before  |  after  |
|-----------|---------:|--------:|
| libstd    |   8.324  |  6.703  |
| stdtest   |  47.674  | 46.857  |
| libsyntax |   9.918  |  8.400  |
auto merge of #12746 : alexcrichton/rust/issue-12743, r=brson

The arguments were accidentally swapped in the wrong order.

Closes #12743
std: stop `vec!()` warning about unused mutability.

If no arguments are given to `vec!` then no pushes are emitted and
so the compiler (rightly) complains that the mutability of `temp` is
never used.

This behaviour is rather annoying for users.