Revert vendor directory to support old golang (GOPATH mode)

gomodule is still in progress to migrate for now, hence multus
team decide to keep vendor directory to support build without
gomodule.

vendor/github.com/vishvananda/netlink/order.go

@@ -0,0 +1,32 @@
+package netlink
+
+import (
+	"encoding/binary"
+
+	"github.com/vishvananda/netlink/nl"
+)
+
+var (
+	native       = nl.NativeEndian()
+	networkOrder = binary.BigEndian
+)
+
+func htonl(val uint32) []byte {
+	bytes := make([]byte, 4)
+	binary.BigEndian.PutUint32(bytes, val)
+	return bytes
+}
+
+func htons(val uint16) []byte {
+	bytes := make([]byte, 2)
+	binary.BigEndian.PutUint16(bytes, val)
+	return bytes
+}
+
+func ntohl(buf []byte) uint32 {
+	return binary.BigEndian.Uint32(buf)
+}
+
+func ntohs(buf []byte) uint16 {
+	return binary.BigEndian.Uint16(buf)
+}