add vendor data

vendor/golang.org/x/net/internal/socket/sys.go

@@ -0,0 +1,23 @@
+// 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"
+)
+
+// NativeEndian is the machine native endian implementation of ByteOrder.
+var NativeEndian binary.ByteOrder
+
+func init() {
+	i := uint32(1)
+	b := (*[4]byte)(unsafe.Pointer(&i))
+	if b[0] == 1 {
+		NativeEndian = binary.LittleEndian
+	} else {
+		NativeEndian = binary.BigEndian
+	}
+}