[PATCH] uml: include stddef.h correctly

We were not including stddef.h in files that used offsetof.

One file was also including linux/stddef.h for no perciptible reason.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>