gstddef.h: Back out change of Sep 15 (handles Sun lossage).

Prevented bootstrapping.

From-SVN: r5372

gcc/ginclude/stddef.h

@@ -13,6 +13,10 @@
 #define _ANSI_STDDEF_H
 #endif
 
+#ifndef __sys_stdtypes_h
+/* This avoids lossage on SunOS but only if stdtypes.h comes first.
+   There's no way to win with the other order!  Sun lossage.  */
+
 /* On 4.3bsd-net2, make sure ansi.h is included, so we have
    one less case to deal with in the following.  */
 #if defined (__BSD_NET2__) || defined (____386BSD____)
@@ -199,6 +203,8 @@ typedef __WCHAR_TYPE__ wchar_t;
 #endif
 #endif /* _ANSI_H_ */
 
+#endif /* __sys_stdtypes_h */
+
 /* A null pointer constant.  */
 
 #if defined (_STDDEF_H) || defined (__need_NULL)