add vendor

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

@@ -0,0 +1,15 @@
+// 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
+
+import "net"
+
+// A payloadHandler represents the IPv6 datagram payload handler.
+type payloadHandler struct {
+	net.PacketConn
+	rawOpt
+}
+
+func (c *payloadHandler) ok() bool { return c != nil && c.PacketConn != nil }