[C++11] Use std::atomic instead of LLVM's.

No intended functionality change.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@202652 91177308-0d34-0410-b5e6-96231b3b80d8
[C++11] ASTMatchers: Use standard static_assert and type traits.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@202653 91177308-0d34-0410-b5e6-96231b3b80d8
Simplifying attribute generation with range-based for loops. No functional changes intended.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@202654 91177308-0d34-0410-b5e6-96231b3b80d8
Adding some cross references to the sanitizer attribute documentation. Removes a Sphinx warning pointed out by Sean Silva.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@202655 91177308-0d34-0410-b5e6-96231b3b80d8