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/internal/socket/sys.go

@@ -1,33 +0,0 @@
-// Copyright 2017 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 socket
-
-import (
-	"encoding/binary"
-	"unsafe"
-)
-
-var (
-	// NativeEndian is the machine native endian implementation of
-	// ByteOrder.
-	NativeEndian binary.ByteOrder
-
-	kernelAlign int
-)
-
-func init() {
-	i := uint32(1)
-	b := (*[4]byte)(unsafe.Pointer(&i))
-	if b[0] == 1 {
-		NativeEndian = binary.LittleEndian
-	} else {
-		NativeEndian = binary.BigEndian
-	}
-	kernelAlign = probeProtocolStack()
-}
-
-func roundup(l int) int {
-	return (l + kernelAlign - 1) & ^(kernelAlign - 1)
-}