slab: Fix comment on #endif

This #endif in slab.h is described as closing the inner block while it's for
the big CONFIG_NUMA one. That makes reading the code a bit harder.

This trivial patch fixes the comment.
Signed-off-by: Pascal Terjan <pterjan@mandriva.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

include/linux/slab.h

@@ -285,7 +285,7 @@ extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, void *);
 #define kmalloc_node_track_caller(size, flags, node) \
 	kmalloc_track_caller(size, flags)
 
-#endif /* DEBUG_SLAB */
+#endif /* CONFIG_NUMA */
 
 /*
  * Shortcuts