archive.c: remove implicit dependency the_repository

The new "repo" field in archive_args has been added since b612ee202a
(archive.c: avoid access to the_index - 2018-08-13). Use it instead of
hard coding the_repository.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

archive.c

@@ -391,7 +391,7 @@ static void parse_treeish_arg(const char **argv,
 	if (get_oid(name, &oid))
 		die("Not a valid object name");
 
-	commit = lookup_commit_reference_gently(the_repository, &oid, 1);
+	commit = lookup_commit_reference_gently(ar_args->repo, &oid, 1);
 	if (commit) {
 		commit_sha1 = commit->object.oid.hash;
 		archive_time = commit->date;