Move the simple can_do_mlock() check before the full rlimits based
restriction checks for mlock() and mlockall().  As it is, the check
adds nothing.  This has a side-effect of eliminating an unnecessary call
to can_do_mlock() on the munlockall() path.
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>