RTPRF_EXPIRING
if (rt->rt_flags & RTPRF_EXPIRING) {
rt->rt_flags &= ~RTPRF_EXPIRING;
if ((rt->rt_flags & (RTF_WASCLONED | RTPRF_EXPIRING)) != RTF_WASCLONED)
rt->rt_flags |= RTPRF_EXPIRING;
if (rt->rt_flags & RTPRF_EXPIRING) {