This change intends to convert all kernel rtsock interactions in route(8) to Netlink.
Based on the WITHOUT_NETLINK_SUPPORT src.conf(5) variable, route(8) now fully operates either via Netlink or via rtsock/sysctl.
The default (compile-time) is Netlink.
The output for route delete/add/get/flush is targeted to be exactly the same (apart from some error handling cases).
The output for the route monitor has been changed to improve readability and support netlink models.
The current deficiencies:
- exact-match (route -n get a.b.c.d/e) does not work
- route monitor does not show the change originator (unless it's kernel).