Url events don't work when an "action" option is configured

<event-bindings>
   <event type="url" trigger="source-connect">
      ...
      ...
      <option name="action" value="mount_add" />

Bug is in event_url.c:event_get_url() https://gitlab.xiph.org/xiph/icecast-server/blob/master/src/event_url.c#L134

Should be free(self->action) not free(self->url)