SLUB: move tracking definitions and check_valid_pointer() away from debug code

Move the tracking definitions and the check_valid_pointer() function away from
the debugging related functions.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>