udev: fix unlikely descriptor leak

modules/services_discovery/udev.c

@@ -535,7 +535,8 @@ static char *disc_get_mrl (struct udev_device *dev)
     val = udev_device_get_property_value (dev, "ID_CDROM_MEDIA_STATE");
     if (val == NULL)
     {   /* Force probing of the disc in the drive if any. */
-        int fd = open (node, O_RDONLY);
+        int fd = open (node, O_RDONLY|O_CLOEXEC);
+        if (fd != -1)
             close (fd);
         return NULL;
     }