Correct a long-standing problem in moea{,64}_pvo_enter() that was revealed
by the combination of r268591 and r269134: When we attempt to add the
wired attribute to an existing mapping, moea{,64}_pvo_enter() do nothing.
(They only set the wired attribute on newly created mappings.)

Tested by:	andreast
List one file per line in the Makefiles.  This makes it easier to read
diffs when a file is added or removed.

MFC after:	2 weeks