Tread TSan LLVM flags to driver: add TSan controlling flags to clang.

Summary:
New clang flags, all default to true:
-f[no-]sanitize-thread-data-races
-f[no-]sanitize-thread-stack-traces
-f[no-]sanitize-thread-atomics

Reviewers: dvyukov, pcc, eugenis

Subscribers: pcc, cfe-commits

Patch by Alex Shlyapnikov.

Differential Revision: https://reviews.llvm.org/D26461

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@286669 91177308-0d34-0410-b5e6-96231b3b80d8