TUN-1615: revert miekg/dns to last known working revision

The last known good commit is 6da3249dfb57fbaa16efafcd8744cee8809d80cd before the first release tag.

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

@@ -1,56 +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
-
-// TrafficClass returns the traffic class field value for outgoing
-// packets.
-func (c *genericOpt) TrafficClass() (int, error) {
-	if !c.ok() {
-		return 0, errInvalidConn
-	}
-	so, ok := sockOpts[ssoTrafficClass]
-	if !ok {
-		return 0, errOpNoSupport
-	}
-	return so.GetInt(c.Conn)
-}
-
-// SetTrafficClass sets the traffic class field value for future
-// outgoing packets.
-func (c *genericOpt) SetTrafficClass(tclass int) error {
-	if !c.ok() {
-		return errInvalidConn
-	}
-	so, ok := sockOpts[ssoTrafficClass]
-	if !ok {
-		return errOpNoSupport
-	}
-	return so.SetInt(c.Conn, tclass)
-}
-
-// HopLimit returns the hop limit field value for outgoing packets.
-func (c *genericOpt) HopLimit() (int, error) {
-	if !c.ok() {
-		return 0, errInvalidConn
-	}
-	so, ok := sockOpts[ssoHopLimit]
-	if !ok {
-		return 0, errOpNoSupport
-	}
-	return so.GetInt(c.Conn)
-}
-
-// SetHopLimit sets the hop limit field value for future outgoing
-// packets.
-func (c *genericOpt) SetHopLimit(hoplim int) error {
-	if !c.ok() {
-		return errInvalidConn
-	}
-	so, ok := sockOpts[ssoHopLimit]
-	if !ok {
-		return errOpNoSupport
-	}
-	return so.SetInt(c.Conn, hoplim)
-}