3373 gcc >= 4.5 concerns about offsetof()

@@ -41,12 +41,10 @@
  */
 
 #ifndef _ISO_STDDEF_ISO_H
 #define _ISO_STDDEF_ISO_H
 
-#pragma ident   "%Z%%M% %I%     %E% SMI" /* SVr4.0 1.5 */
-
 #include <sys/isa_defs.h>
 
 #ifdef  __cplusplus
 extern "C" {
 #endif

@@ -86,11 +84,15 @@
 #endif /* end of namespace std */
 
 #if __cplusplus >= 199711L
 #define offsetof(s, m)  (std::size_t)(&(((s *)0)->m))
 #else
-#define offsetof(s, m)  (size_t)(&(((s *)0)->m))
+#if defined(__GNUC__)
+#define offsetof(s, m)  __builtin_offsetof(s, m)
+#else
+#define offsetof(s, m)  ((size_t)(&(((s *)0)->m)))
+#endif
 #endif
 
 #ifdef  __cplusplus
 }
 #endif