Appletalk to run on FreeBSD 3.0 and up. The mechanism used to add a
non-IP multicast group via SIOCADDMULTI changed between 2.2.x and 3.0,
but bpfiltp.c:pi_addmulti() was not changed to match. Without this
patch, the port will compile but aarpd will not run. (This kind of messes
up everything since the port is built to use Ethertalk Phase 2, and
none of that works without aarpd.)
