Add ThreadSanitizer runs to test suite

It would be good to run a race detector on our code. This may be limited to non-DR-managed apps as DR can cause problems with sanitizers due to its custom memory allocator, generated code, and assembly code. But we know that sanitizers work well with the drmemtrace analyzers. The primary target I'd like to add is the drmemtrace scheduler: e.g., run the scheduler_unit_tests under tsan.