git-fsck-cache: don't complain about lacking references when they are all in packs.

We used to not count them at all, which then made us complain that there
were no refs.

fsck-cache.c

@@ -312,8 +312,10 @@ static int fsck_handle_ref(const char *refname, const unsigned char *sha1)
 
 	obj = lookup_object(sha1);
 	if (!obj) {
-		if (!standalone && has_sha1_file(sha1))
+		if (!standalone && has_sha1_file(sha1)) {
+			default_refs++;
 			return 0; /* it is in a pack */
+		}
 		error("%s: invalid sha1 pointer %s", refname, sha1_to_hex(sha1));
 		/* We'll continue with the rest despite the error.. */
 		return 0;