[asan] use some LIKELY/UNLIKELY

llvm-svn: 208776
diff --git a/compiler-rt/lib/asan/asan_stack.h b/compiler-rt/lib/asan/asan_stack.h
index 5db1d1a..032f729d 100644
--- a/compiler-rt/lib/asan/asan_stack.h
+++ b/compiler-rt/lib/asan/asan_stack.h
@@ -32,7 +32,7 @@
 #else
   AsanThread *t;
   stack->size = 0;
-  if (asan_inited) {
+  if (LIKELY(asan_inited)) {
     if ((t = GetCurrentThread()) && !t->isUnwinding()) {
       uptr stack_top = t->stack_top();
       uptr stack_bottom = t->stack_bottom();