Make "OptimisticData auto" mean it's on?

static int
optimistic_data_enabled(void)
{
  const or_options_t *options = get_options();
  if (options->OptimisticData < 0) {
    /* XXX023 consider having auto default to 1 rather than 0 before
     * the 0.2.3 branch goes stable. See bug 3617. -RD */
    const int32_t enabled =
      networkstatus_get_param(NULL, "UseOptimisticData", 0, 0, 1);
    return (int)enabled;
  }
  return options->OptimisticData;
}