ipc: constify ipc_ops

ipc: constify ipc_ops

There is no need to recreate the very same ipc_ops structure on every
kernel entry for msgget/semget/shmget.  Just declare it static and be done
with it.  While at it, constify it as we don't modify the structure at
runtime.

Found in the PaX patch, written by the PaX Team.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: PaX Team <pageexec@freemail.hu>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>