vadefs.h: be even more conservative and only define the macros if already defined

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@219745 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Headers/vadefs.h b/lib/Headers/vadefs.h
index 85cbfc37a3a37304d9562bd3167b25c9bb03396c..cb997fbf66c48e657821ffd1aae51f4b6874267c 100644 (file)
--- a/lib/Headers/vadefs.h
+++ b/lib/Headers/vadefs.h
@@ -34,17 +34,16 @@
 /* Override macros from vadefs.h with definitions that work with Clang. */
 #ifdef _crt_va_start
 #undef _crt_va_start
+#define _crt_va_start(ap, param) __builtin_va_start(ap, param)
 #endif
 #ifdef _crt_va_end
 #undef _crt_va_end
+#define _crt_va_end(ap)          __builtin_va_end(ap)
 #endif
 #ifdef _crt_va_arg
 #undef _crt_va_arg
-#endif
-
-#define _crt_va_start(ap, param) __builtin_va_start(ap, param)
-#define _crt_va_end(ap)          __builtin_va_end(ap)
 #define _crt_va_arg(ap, type)    __builtin_va_arg(ap, type)
+#endif
 
 #endif
 #endif