Make $message available in message_subscribe_get_subscribers_alter

Currently message_subscribe_get_subscribers implements drupal_alter like so:

drupal_alter('message_subscribe_get_subscribers', $uids, $values);

It would be nice if $message were available to the modules that implement hook_message_subscribe_get_subscribers_alter(). Ex.

drupal_alter('message_subscribe_get_subscribers', $uids, $values, $message);