[tsan] rudimentary support for deadlock detector in tsan (nothing really works yet except for a single tiny test). Also rename tsan's DeadlockDetector to InternalDeadlockDetector

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@201407 91177308-0d34-0410-b5e6-96231b3b80d8