[PATCH] slab: replace kmem_cache_t with struct kmem_cache

Replace uses of kmem_cache_t with proper struct kmem_cache in mm/slab.c.
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>