Revert "udevd: simplify sigterm check"

This reverts commit 47e737dc13 - it
introduced a use-after-free.  The only way the code would get simpler
is with a cleanup function, but eh, not worth it for just this one
bit.

Reviewed by kay on IRC.

src/udev/udevd.c

@@ -314,10 +314,12 @@ static void worker_new(struct event *event)
                         udev_device_unref(dev);
                         dev = NULL;
 
-                        udev_event_unref(udev_event);
-
-                        if (udev_event->sigterm)
+                        if (udev_event->sigterm) {
+                                udev_event_unref(udev_event);
                                 goto out;
+                        }
+
+                        udev_event_unref(udev_event);
 
                         /* wait for more device messages from main udevd, or term signal */
                         while (dev == NULL) {