Add clang thread safety annotations to mutex and lock_guard. Patch by

This adds clang thread safety annotations to std::mutex and
std::lock_guard so code using these types can use these types directly
instead of having to wrap the types to provide annotations. These checks
when enabled by -Wthread-safety provide simple but useful static
checking to detect potential race conditions.
See for details.

This patch was reviewed in

git-svn-id: 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed