Other protocols do this as soon as they discover over what interface the
packet will be routed, but LLC isn't routable, so, to provide similar
semantics to the other protocols, I'm just binding it to the first interface
of the type specified, perhaps we'll need a tunable for this or some sort of
routing table done manually by the admin, later we'll see, for now this
allows an application like openssh, with patched getaddrinfo/getnameinfo to
use PF_LLC sockets with a very small patch.