[PATCH] IPC namespace core

This patch set allows to unshare IPCs and have a private set of IPC objects
(sem, shm, msg) inside namespace.  Basically, it is another building block of
containers functionality.

This patch implements core IPC namespace changes:
- ipc_namespace structure
- new config option CONFIG_IPC_NS
- adds CLONE_NEWIPC flag
- unshare support

[clg@fr.ibm.com: small fix for unshare of ipc namespace]
[akpm@osdl.org: build fix]
Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Signed-off-by: Kirill Korotaev <dev@openvz.org>
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>