go.net/ipv6: new package

Package ipv6 implements IP-level socket options for the Internet
Protocol version 6. It also provides datagram based network I/O
methods specific to the IPv6 and higher layer protocols.

Fixes golang/go#5538.

R=dave
CC=golang-dev
https://golang.org/cl/9843044
diff --git a/ipv6/icmp_plan9.go b/ipv6/icmp_plan9.go
new file mode 100644
index 0000000..b97c828
--- /dev/null
+++ b/ipv6/icmp_plan9.go
@@ -0,0 +1,22 @@
+// Copyright 2013 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.
+
+package ipv6
+
+type rawICMPFilter struct {
+	// TODO(mikio): Implement this
+}
+
+func (f *rawICMPFilter) set(typ ICMPType, block bool) {
+	// TODO(mikio): Implement this
+}
+
+func (f *rawICMPFilter) setAll(block bool) {
+	// TODO(mikio): Implement this
+}
+
+func (f *rawICMPFilter) willBlock(typ ICMPType) bool {
+	// TODO(mikio): Implement this
+	return false
+}