Multicast address handling is not consistent across all BSDs. Move
the multicast address handling code into OS dependent files. This
will be needed for OpenBSD support.
R=mikioh.mikioh, golang-dev
CC=golang-dev
https://golang.org/cl/4809074
This CL enables to list the multicast, joined group addresses
for a specific interface by using Interface.MulticastAddrs
method.
R=rsc
CC=golang-dev
https://golang.org/cl/4808062
This CL introduces new API into package net to identify the network
interface. A functionality of new API is very similar to RFC3493 -
"Interface Identification".
R=r, gri, bradfitz, robert.hencke, fullung, rsc
CC=golang-dev
https://golang.org/cl/4437087