When collecting the list of objects to pack in get_object_list(), we
pass our rev_info struct around to some functions that don't need it.
This is due to 03a9683d22 (Simplify is_kept_pack(), 2009-02-28), where
the kept-pack handling was moved out of the revision machinery.
Let's drop these unused parameters.
Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>