udevadm: settle - fix timeout

The timeout wasn't working when settle was run as root:
  # udevadm control --stop-exec-queue
  # udevadm trigger
  # udevadm settle --timeout=1
  ... (hangs)

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>

udev/udevadm-settle.c

@@ -167,6 +167,7 @@ int udevadm_settle(struct udev *udev, int argc, char *argv[])
 			sigprocmask(SIG_BLOCK, &mask, &oldmask);
 			if (udev_ctrl_send_settle(uctrl) > 0)
 				sigsuspend(&oldmask);
+			sigprocmask(SIG_SETMASK, &oldmask, NULL);
 			udev_ctrl_unref(uctrl);
 		}
 	}