net: add multicast stubs for openbsd

Add multicast stubs and sync with recent changes.

R=golang-dev, mikioh.mikioh
CC=golang-dev
https://golang.org/cl/4838058

src/pkg/net/Makefile

@@ -86,11 +86,13 @@ GOFILES_linux+=cgo_stub.go
 endif
 
 GOFILES_openbsd=\
-	dnsclient.go\
+	dnsclient_unix.go\
 	dnsconfig.go\
 	fd.go\
 	file.go\
 	interface_bsd.go\
+	interface_openbsd.go\
+	lookup_unix.go\
 	newpollserver.go\
 	port.go\
 	sendfile_stub.go\

src/pkg/net/interface_openbsd.go

+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Network interface identification for OpenBSD
+
+package net
+
+import "os"
+
+// If the ifindex is zero, interfaceMulticastAddrTable returns
+// addresses for all network interfaces.  Otherwise it returns
+// addresses for a specific interface.
+func interfaceMulticastAddrTable(ifindex int) ([]Addr, os.Error) {
+	return nil, nil
+}