git p4: fix writable file after rename or copy

git p4: fix writable file after rename or copy

The way rename works is with a "p4 integrate", optionally
followed by a "p4 edit" if the change is not a 100% rename.
Contents are generated by applying a patch, not doing a file
system rename.  Copy is similar.

In this case, p4 does not fix the permissions back to read-only.
Make sure this happens by calling "p4 sync -f".

Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>