TSan can produce false positives in code that uses C++11 threading, as it doesn't see synchronization inside standard library. See http://lists.cs.uiuc.edu/pipermail/cfe-dev/2014-February/035408.html for an example of such case. We may build custom TSan-instrumented version libcxx to fight with that. This change adds build rules for libcxx_tsan and integrates it into testing infrastructure. llvm-svn: 208737