[PATCH] [Sanitizers] Enable stack traces on FreeBSD

[Alexander Potapenko]

THREADLOCAL is indeed supported on OSX (we haven't switched to using it yet, though). IIRC TLS support isn't finished on Android yet.

The change looks good to me.

================
Comment at: lib/sanitizer_common/sanitizer_stacktrace.h:32
@@ -31,1 +31,3 @@
 
+// Fast unwind is the only option on Mac.
+#if SANITIZER_MAC
----------------
We'll need to revisit this when slow unwind works on Mac. Please add a comment linking to https://code.google.com/p/address-sanitizer/issues/detail?id=137

http://reviews.llvm.org/D6086