ipc: fix wrong comments

This patch fixes the wrong / obsolete comments in the ipc code.  Also adds
a missing lock around ipc_get_maxid() in shm_get_stat().

Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --cc ipc/msg.c
Simple merge

diff --cc ipc/sem.c
Simple merge

diff --cc ipc/shm.c
Simple merge

diff --cc ipc/util.c
Simple merge

diff --cc ipc/util.h
Simple merge