tsan: remove stats from ThreadState ifndef TSAN_COLLECT_STATS

Issue 89: Uses a lot of memory for each goroutine
https://code.google.com/p/thread-sanitizer/issues/detail?id=89

llvm-svn: 229112
diff --git a/compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cc b/compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cc
index e026217..0cb2fcb 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cc
+++ b/compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cc
@@ -145,7 +145,9 @@
   AllocatorThreadFinish(thr);
 #endif
   thr->~ThreadState();
+#ifdef TSAN_COLLECT_STATS
   StatAggregate(ctx->stat, thr->stat);
+#endif
   thr = 0;
 }