Quash a whole bunch of warnings

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@145624 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/mutex b/include/mutex
index 8bc6b80..62b733f 100644
--- a/include/mutex
+++ b/include/mutex
@@ -534,7 +534,7 @@
 void
 call_once(once_flag& __flag, _Callable&& __func, _Args&&... __args)
 {
-    if (__builtin_expect(__flag.__state_ , ~0ul) != ~0ul)
+    if (__flag.__state_ != ~0ul)
     {
         typedef tuple<typename decay<_Callable>::type, typename decay<_Args>::type...> _Gp;
         __call_once_param<_Gp> __p(_Gp(__decay_copy(_VSTD::forward<_Callable>(__func)),