packfile: rename close_all_packs to close_object_store

The close_all_packs() method is now responsible for more than just pack-files.
It also closes the commit-graph and the multi-pack-index. Rename the function
to be more descriptive of its larger role. The name also fits because the
input parameter is a raw_object_store.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

object.c

@@ -517,7 +517,7 @@ void raw_object_store_clear(struct raw_object_store *o)
 	o->loaded_alternates = 0;
 
 	INIT_LIST_HEAD(&o->packed_git_mru);
-	close_all_packs(o);
+	close_object_store(o);
 	o->packed_git = NULL;
 }