[PATCH] [Tsan] Fix references to libc entities in tsan_interceptors.cc on FreeBSD

[Ed Maste]

================
Comment at: lib/tsan/rtl/tsan_interceptors.cc:2256
@@ -2243,2 +2255,3 @@
+#if !SANITIZER_FREEBSD
   mallopt(1, 0);  // M_MXFAST
   mallopt(-3, 32*1024);  // M_MMAP_THRESHOLD
----------------
FreeBSD has mallctl() as a rough analog if tuning is needed.

http://reviews.llvm.org/D5663