[PATCH] mm: add /proc/zoneinfo

Add /proc/zoneinfo file to display information about memory zones.  Useful
to analyze VM behaviour.

Signed-off-by: Nikita Danilov <nikita@clusterfs.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>