[PATCH] [Tsan] Do not intercept non-FreeBSD functions on FreeBSD

[Alexey Samsonov]

I think we need magic similar to sanitizer_common_interceptors.inc - define TSAN_INTERCEPT_FOO depending on the platform, define or not define TSAN_INTERCEPTOR(foo, ...) depending on its value, and define TSAN_MAYBE_INTERCEPT(foo) to either TSAN_INTERCEPT(foo), or empty statement.

http://reviews.llvm.org/D5858