Fix dependencies

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

@@ -1,22 +0,0 @@
-// 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
-
-func (f *icmpv6Filter) accept(typ ICMPType) {
-	// TODO(mikio): implement this
-}
-
-func (f *icmpv6Filter) block(typ ICMPType) {
-	// TODO(mikio): implement this
-}
-
-func (f *icmpv6Filter) setAll(block bool) {
-	// TODO(mikio): implement this
-}
-
-func (f *icmpv6Filter) willBlock(typ ICMPType) bool {
-	// TODO(mikio): implement this
-	return false
-}