Switch to using the dep tool and update all the dependencies

vendor/golang.org/x/net/ipv6/icmp_stub.go

@@ -0,0 +1,23 @@
+// 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.
+
+// +build nacl plan9
+
+package ipv6
+
+type icmpv6Filter struct {
+}
+
+func (f *icmpv6Filter) accept(typ ICMPType) {
+}
+
+func (f *icmpv6Filter) block(typ ICMPType) {
+}
+
+func (f *icmpv6Filter) setAll(block bool) {
+}
+
+func (f *icmpv6Filter) willBlock(typ ICMPType) bool {
+	return false
+}