rust-lang/rust — pull request #20367 by retep998 (2014-12-31 08:11:55+00:00)
Title: Change Mutex to use SRWLock on Windows.

Also adjusted some of the FFI definitions because apparently they don't use the long pointer prefix.
Gives a free performance boost because `SRWLock` is several times faster than `CriticalRegion` on every Windows system tested.
Fixes #19962