Index: lib/Headers/stddef.h
===================================================================
--- lib/Headers/stddef.h	(revision 155540)
+++ lib/Headers/stddef.h	(working copy)
@@ -52,10 +52,10 @@
 #  define NULL ((void*)0)
 #endif
 
+#endif /* __STDDEF_H */
+
 #define offsetof(t, d) __builtin_offsetof(t, d)
 
-#endif /* __STDDEF_H */
-
 /* Some C libraries expect to see a wint_t here. Others (notably MinGW) will use
 __WINT_TYPE__ directly; accommodate both by requiring __need_wint_t */
 #if defined(__need_wint_t)