Squash some small bugs in pts(4).

- Don't return a negative errno when using an unknown ioctl() on a
  pseudo-terminal master device. Be sure to convert ENOIOCTL to ENOTTY,
  just like the TTY layer does.

- Even though we should return st_rdev of the master device node when
  emulating pty(4) devices, FIODGNAME should still return the name of
  the slave device. Otherwise ptsname(3) and ttyname(3) return an
  invalid device name.

sys/kern/tty_pts.c

@@ -290,11 +290,6 @@ ptsdev_ioctl(struct file *fp, u_long cmd, void *data,
 
 		/* Reverse device name lookups, for ptsname() and ttyname(). */
 		fgn = data;
-#ifdef PTS_EXTERNAL
-		if (psc->pts_cdev != NULL)
-			p = devtoname(psc->pts_cdev);
-		else
-#endif /* PTS_EXTERNAL */
 		p = tty_devname(tp);
 		i = strlen(p) + 1;
 		if (i > fgn->len)
@@ -385,6 +380,8 @@ ptsdev_ioctl(struct file *fp, u_long cmd, void *data,
 	tty_lock(tp);
 	error = tty_ioctl(tp, cmd, data, td);
 	tty_unlock(tp);
+	if (error == ENOIOCTL)
+		error = ENOTTY;
 
 	return (error);
 }