[tsan] Fix freebsd build.

Summary:
Freebsd doesn't have <sys/personality.h>, so call personality() only in
SANITIZER_LINUX.

Reviewers: llvm-commits, dvyukov, zatrazz, rengolin, beanz

Subscribers: beanz, emaste

Differential Revision: http://reviews.llvm.org/D18785

llvm-svn: 265378