Make sendto() work for IPv4 by setting the IP_MULTICAST_IF socket option.
Allows this port to drop the dependency on net/libnet and stop using the
associated sendto() replacement hack (which supports only IPv4).
Make IPv6 work: Fix adding/deleting IPv6 routes, and don't complain
about a missing net.inet6.icmp6.rediraccept sysctl.
Also enable the verbose build so build logs show the commands
being used to compile things.
ok danj@ sthen@
d1ead8c734