C files should include the header files that prototype their functions.

Eliminates a sparse warning:
warning: symbol 'check_bugs' was not declared. Should it be static?
Signed-off-by: Josh Triplett <josh@kernel.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>