[PATCH] [Tsan] Fix the thread_name tests to build on FreeBSD

[Ed Maste]

> Emaste says there is pthread_set_name_np on freebsd; if it's so, use it in the test and intercept it in tsan_interceptors.cc.

pthread_set_name_np has existed on FreeBSD since 1998 so there's no need for a version check either.

http://reviews.llvm.org/D5855