archive: do not let on-disk mode leak to zip archives

When the "--add-file" option is used to add the contents from an
untracked file to the archive, the permission mode bits for these
files are sent to the archive-backend specific "write_entry()"
method as-is.  We normalize the mode bits for tracked files way
before we pass them to the write_entry() method; we should do the
same here.

This is not strictly needed for "tar" archive-backend, as it has its
own code to further clean them up, but "zip" archive-backend is not
so well prepared.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

archive.c

@@ -342,7 +342,7 @@ int write_archive_entries(struct archiver_args *args,
 		else
 			err = write_entry(args, &fake_oid, path_in_archive.buf,
 					  path_in_archive.len,
-					  info->stat.st_mode,
+					  canon_mode(info->stat.st_mode),
 					  content.buf, content.len);
 		if (err)
 			break;