[PATCH] Work around gcc 3.5 offsetof bug

Current gcc 3.5 doesn't compile a x86-64 kernel, because it doesn't
recognize the offsetof used in asm-offset.c to be constant.

Use __builtin_offsetof for this instead.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/compiler-gcc3.h

@@ -28,3 +28,7 @@
 #if __GNUC_MINOR__ >= 4
 #define __must_check __attribute__((warn_unused_result))
 #endif
+
+#if __GNUC_MINOR__ >= 5
+#define __compiler_offsetof(a,b) __builtin_offsetof(a,b)
+#endif

include/linux/stddef.h

 #ifndef _LINUX_STDDEF_H
 #define _LINUX_STDDEF_H
 
+#include <linux/compiler.h>
+
 #undef NULL
 #if defined(__cplusplus)
 #define NULL 0
@@ -9,6 +11,10 @@
 #endif
 
 #undef offsetof
+#ifdef __compiler_offsetof
+#define offsetof(TYPE,MEMBER) __compiler_offsetof(TYPE,MEMBER)
+#else
 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
+#endif
 
 #endif