No functional changes. Most of the routing flags are stored in the netxtop instead of rtentry. Rename rt->rt_flags to rt->rte_flags to simplify reading/modifying code checking routing flags. In the new multipath code, rt->rt_nhop may actually point to nexthop group instead of nhop. To ease transition, reduce the amount of rt->rt_nhop->... accesses. Differential Revision: https://reviews.freebsd.org/D26156