Cleanup to show_free_areas() from Bill Irwin:

show_free_areas() and show_free_areas_core() is a mess.
(1) it uses a bizarre and ugly form of list iteration to walk buddy lists
        use standard list functions instead
(2) it prints the same information repeatedly once per-node
        rationalize the braindamaged iteration logic
(3) show_free_areas_node() is useless and not called anywhere
        remove it entirely
(4) show_free_areas() itself just calls show_free_areas_core()
        remove show_free_areas_core() and do the stuff directly
(5) SWAP_CACHE_INFO is always #defined, remove it
(6) INC_CACHE_INFO() doesn't use the do { } while (0) construct

This patch also includes Matthew Dobson's patch which removes
mm/numa.c:node_lock.  The consensus is that it doesn't do anything now
that show_free_areas_node() isn't there.