Make sparse checker work for userspace files - it normally gets -nostdinc
separately, so avoid having it for userspace files. Also, add -D$(SUBARCH)
for multiarch hosts (i.e. AMD64 with compatibility headers).
It works, the only problem is a bit of bogus warnings for system headers, but
they're not too many.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>