add an experimental tag for Gc<T> due to cycles

This type isn't yet very useful since it only pretends cycles won't be
a problem. Anyone using it should be made aware that they're going to
leak.
Flag failure functions as inline(never)

The failure functions are generic, meaning they're candidates for getting
inlined across crates. This has been happening, leading to monstrosities like
that found in #11549. I have verified that the codegen is *much* better now that
we're not inlining the failure path (the slow path).
register snapshots
remove the concept of managed-unique from libstd

Closes #11545
Add a configure to disable libstd version injection

We'll use this when building snapshots so we can upgrade freely, but all
compilers will inject a version by default.
auto merge of #11523 : alexcrichton/rust/stage3, r=brson

This should go back to the old behavior while preserving the snapshot ease.
Use the least significant beat to determine if int/uint is even
libsyntax: Remove the obsolete ability to parse from substrings.

This was used by the quasiquoter.
auto merge of #11543 : thestinger/rust/gc, r=cmr

This type isn't yet very useful since it only pretends cycles won't be
a problem. Anyone using it should be made aware that they're going to
leak.
Allow more "error" values in try_recv()

This should allow callers to know whether the channel was empty or disconnected
without having to block.

Closes #11087
auto merge of #11112 : alexcrichton/rust/issue-11087, r=brson

This should allow callers to know whether the channel was empty or disconnected
without having to block.

Closes #11087
path: Fix joining Windows path when the receiver is "C:"

WindowsPath::new("C:").join("a") produces r"C:\a". This is incorrect.
It should produce "C:a".
auto merge of #11550 : alexcrichton/rust/noinline, r=thestinger

The failure functions are generic, meaning they're candidates for getting
inlined across crates. This has been happening, leading to monstrosities like
that found in #11549. I have verified that the codegen is *much* better now that
we're not inlining the failure path (the slow path).
auto merge of #11568 : FlaPer87/rust/even, r=alexcrichton

This implementation should be a bit more optimal than calling `self.is_multiple_of(&2)`
Merge Bitwise and BitCount traits and remove from prelude, along with Bounded

One less trait in std::num, and three less exported in the prelude.
auto merge of #11565 : mozilla/rust/snapshot, r=huonw
Only build LLVM tools Rust needs.
Update docs index to use lists

Also include a missing link to the rustdoc manual
auto merge of #11574 : neeee/rust/master, r=alexcrichton

Reverted according to https://github.com/mozilla/rust/issues/11458#issuecomment-32269477. Fixes #11458.
auto merge of #11548 : bjz/rust/bitwise, r=alexcrichton

One less trait in `std::num` and three less exported in the prelude.

cc. #10387