Add a note in the user manual that tsan is not supported on Mac.

Patch from Sean McBride <sean@rogue-research.com>!


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203260 91177308-0d34-0410-b5e6-96231b3b80d8
[C++11] Replacing IndirectFieldDecl iterators chain_begin() and chain_end() with iterator_range chains(). Updating all of the usages of the iterators with range-based for loops.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203261 91177308-0d34-0410-b5e6-96231b3b80d8