rev-list: fix --verify-objects --quiet becoming --objects

rev-list: fix --verify-objects --quiet becoming --objects

When --quiet is specified, finish_object() is called instead of
show_object(). The latter is in charge of --verify-objects and
will be skipped  if --quiet is specified.

Move the code up to finish_object(). Also pass the quiet flag along
and make it always call show_* functions to avoid similar problems in
future.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>