odb/packed: fix memory leaks when freeing source

When freeing a "packed" source we don't close either its packs nor its
multi-pack indices. This can cause memory leaks in case we create an
ad-hoc packed source. As we used to always link packed sources to the
main object database we never noticed this issue until now, but it's
going to surface in subsequent commits where we stop linking them.

Plug the memory leaks by closing the source first.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

odb/source-packed.c

@@ -844,6 +844,7 @@ static void odb_source_packed_free(struct odb_source *source)
 
 	chdir_notify_unregister(odb_source_packed_reparent, packed);
 
+	odb_source_close(source);
 	for (struct packfile_list_entry *e = packed->packs.head; e; e = e->next)
 		free(e->pack);
 	packfile_list_clear(&packed->packs);