stddef.h: move offsetofend inside #ifndef/#endif guard, neaten

Commit 3876488444e7 ("include/stddef.h: Move offsetofend() from vfio.h
to a generic kernel header") added offsetofend outside the normal
include #ifndef/#endif guard.  Move it inside.

Miscellanea:

o remove unnecessary blank line
o standardize offsetof macros whitespace style

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/stddef.h

@@ -3,7 +3,6 @@
 
 #include <uapi/linux/stddef.h>
 
-
 #undef NULL
 #define NULL ((void *)0)
 
@@ -14,10 +13,9 @@ enum {
 
 #undef offsetof
 #ifdef __compiler_offsetof
-#define offsetof(TYPE,MEMBER) __compiler_offsetof(TYPE,MEMBER)
+#define offsetof(TYPE, MEMBER)	__compiler_offsetof(TYPE, MEMBER)
 #else
-#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
-#endif
+#define offsetof(TYPE, MEMBER)	((size_t)&((TYPE *)0)->MEMBER)
 #endif
 
 /**
@@ -28,3 +26,5 @@ enum {
  */
 #define offsetofend(TYPE, MEMBER) \
 	(offsetof(TYPE, MEMBER)	+ sizeof(((TYPE *)0)->MEMBER))
+
+#endif