tty: Open slave peers with O_NOCTTY

We have own mechanism to restore controlling
terminal thus we don't need the kernel to create
it in implicit way.

#2409
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

tty.c

@@ -472,7 +472,7 @@ static int pty_open_slaves(struct tty_info *info)
 	list_for_each_entry(slave, &info->sibling, sibling) {
 		BUG_ON(pty_is_master(slave));
 
-		fd = open(pts_name, slave->tfe->flags);
+		fd = open(pts_name, slave->tfe->flags | O_NOCTTY);
 		if (fd < 0) {
 			pr_perror("Can't open slave %s", pts_name);
 			goto err;