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/addr.go

@@ -0,0 +1,56 @@
+package netlink
+
+import (
+	"fmt"
+	"net"
+	"strings"
+)
+
+// Addr represents an IP address from netlink. Netlink ip addresses
+// include a mask, so it stores the address as a net.IPNet.
+type Addr struct {
+	*net.IPNet
+	Label       string
+	Flags       int
+	Scope       int
+	Peer        *net.IPNet
+	Broadcast   net.IP
+	PreferedLft int
+	ValidLft    int
+}
+
+// String returns $ip/$netmask $label
+func (a Addr) String() string {
+	return strings.TrimSpace(fmt.Sprintf("%s %s", a.IPNet, a.Label))
+}
+
+// ParseAddr parses the string representation of an address in the
+// form $ip/$netmask $label. The label portion is optional
+func ParseAddr(s string) (*Addr, error) {
+	label := ""
+	parts := strings.Split(s, " ")
+	if len(parts) > 1 {
+		s = parts[0]
+		label = parts[1]
+	}
+	m, err := ParseIPNet(s)
+	if err != nil {
+		return nil, err
+	}
+	return &Addr{IPNet: m, Label: label}, nil
+}
+
+// Equal returns true if both Addrs have the same net.IPNet value.
+func (a Addr) Equal(x Addr) bool {
+	sizea, _ := a.Mask.Size()
+	sizeb, _ := x.Mask.Size()
+	// ignore label for comparison
+	return a.IP.Equal(x.IP) && sizea == sizeb
+}
+
+func (a Addr) PeerEqual(x Addr) bool {
+	sizea, _ := a.Peer.Mask.Size()
+	sizeb, _ := x.Peer.Mask.Size()
+	// ignore label for comparison
+	return a.Peer.IP.Equal(x.Peer.IP) && sizea == sizeb
+}