Revert "[PATCH] namespaces: fix exit race by splitting exit"

This reverts commit 7a238fcba0629b6f2edbcd37458bae56fcf36be5 in
preparation for a better and simpler fix proposed by Eric Biederman
(and fixed up by Serge Hallyn)

Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --cc include/linux/nsproxy.h
Simple merge

diff --cc kernel/exit.c
Simple merge

diff --cc kernel/fork.c
Simple merge

diff --cc kernel/nsproxy.c
Simple merge