vendor: add kcp-go package

vendor/golang.org/x/net/ipv4/control_windows.go

@@ -0,0 +1,27 @@
+// Copyright 2012 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 ipv4
+
+import "syscall"
+
+func setControlMessage(fd syscall.Handle, opt *rawOpt, cf ControlFlags, on bool) error {
+	// TODO(mikio): implement this
+	return syscall.EWINDOWS
+}
+
+func newControlMessage(opt *rawOpt) []byte {
+	// TODO(mikio): implement this
+	return nil
+}
+
+func parseControlMessage(b []byte) (*ControlMessage, error) {
+	// TODO(mikio): implement this
+	return nil, syscall.EWINDOWS
+}
+
+func marshalControlMessage(cm *ControlMessage) []byte {
+	// TODO(mikio): implement this
+	return nil
+}