fsck-objects: mark objects reachable from cache-tree

When fsck-objects scanned cache-tree, it forgot to mark the
trees it found reachable and in use.

Signed-off-by: Junio C Hamano <junkio@cox.net>

fsck-objects.c

@@ -446,6 +446,8 @@ static int fsck_cache_tree(struct cache_tree *it)
 
 	if (0 <= it->entry_count) {
 		struct object *obj = parse_object(it->sha1);
+		mark_reachable(obj, REACHABLE);
+		obj->used = 1;
 		if (obj->type != tree_type)
 			err |= objerror(obj, "non-tree in cache-tree");
 	}