mark operator new(std::nothrow) as noalias (aka __attribute__((malloc))

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@159359 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/__config b/include/__config
index 369417c..3df583f 100644
--- a/include/__config
+++ b/include/__config
@@ -391,6 +391,12 @@
 #define _LIBCPP_CONSTEXPR constexpr
 #endif
 
+#ifdef __GNUC__
+#define _NOALIAS __attribute__((malloc))
+#else
+#define _NOALIAS
+#endif
+
 #ifndef __has_feature
 #define __has_feature(__x) 0
 #endif