std: uniform modules titles for doc

This commit uniforms the short title of modules provided by libstd,
in order to make their roles more explicit when glancing at the index.

Signed-off-by: Luca Bruno <lucab@debian.org>
Stop using @ExtCtxt
Remove unecessary extern "Rust" specifiers
Stop passing duplicate parameters in expand
rust.md : update crate attributes.

#[ author = "Jane Doe" ]; raises "warning: unknown crate attribute"
auto merge of #11134 : lucab/rust/lucab/libstd-doc, r=cmr

Uniform the short title of modules provided by libstd, in order to make their roles more explicit when glancing at the index.
Add /doc/{green,native} to .gitignore
Add method .as_mut_slice() to MutableVector

This method is primarily intended to allow for converting a [T, ..N] to
a &mut [T].
Add /doc/{rustc,syntax} to .gitignore
Rename pkgid variables
Rename PkgId to CrateId
Rename uses of PkgId to CrateId in librustpkg
Update Docs to use crateid
Register new snapshots.
Actually block in a windows cvar

Turns out with an argument of 0 the function always returns immediately!

Closes #11003
Fix a deadlock in a libgreen test

Turns out when you grab an OS mutex, you need to be careful about when and where
things are scheduled!
auto merge of #11204 : alexcrichton/rust/issue-11200, r=cmr

Turns out when you grab an OS mutex, you need to be careful about when and where
things are scheduled!

I've confirmed that I could fairly reliably get a deadlock (1 in 100 times ish) before this, and I cannot get a deadlock after this (after 1000+ runs).

Closes #11200
Update llvm.
auto merge of #11181 : luqmana/rust/up-llvm, r=alexcrichton

No longer need to handle GNUEABIHF and hard floats since LLVM should now choose the right default. Fixes #11164.
rustdoc: only filter lines starting with '# ' from the shown code.

Currently any line starting with `#` is filtered from the output,
including line like `#[deriving]`; this patch makes it so lines are only
filtered when followed by a space similar to the current behaviour of
the tutorial/manual tester.