pack-bitmap: uninteresting oid can be outside bitmapped packfile

pack-bitmap: uninteresting oid can be outside bitmapped packfile

bitmap_has_oid_in_uninteresting() only used bitmap_position_packfile(),
not bitmap_position(). So it wouldn't find objects which weren't in the
bitmapped packfile (i.e., ones where we extended the bitmap to handle
loose objects, or objects in other packs).

As we could reuse a delta against such an object it is suboptimal not
to use bitmap_position(), so let's use it instead of
bitmap_position_packfile().

Signed-off-by: Jeff King <redacted>
Signed-off-by: Christian Couder <redacted>
Signed-off-by: Junio C Hamano <redacted>