Initialize rate_limited to false in directory_get_from_hs_dir()

  /* Automatically pick an hs dir if none given. */

  if (!rs_hsdir) {

    bool rate_limited;

    bool rate_limited = false;

    /* Determine responsible dirs. Even if we can't get all we want, work with

     * the ones we have. If it's empty, we'll notice in hs_pick_hsdir(). */