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/xfrm_policy.go

@@ -0,0 +1,74 @@
+package netlink
+
+import (
+	"fmt"
+	"net"
+)
+
+// Dir is an enum representing an ipsec template direction.
+type Dir uint8
+
+const (
+	XFRM_DIR_IN Dir = iota
+	XFRM_DIR_OUT
+	XFRM_DIR_FWD
+	XFRM_SOCKET_IN
+	XFRM_SOCKET_OUT
+	XFRM_SOCKET_FWD
+)
+
+func (d Dir) String() string {
+	switch d {
+	case XFRM_DIR_IN:
+		return "dir in"
+	case XFRM_DIR_OUT:
+		return "dir out"
+	case XFRM_DIR_FWD:
+		return "dir fwd"
+	case XFRM_SOCKET_IN:
+		return "socket in"
+	case XFRM_SOCKET_OUT:
+		return "socket out"
+	case XFRM_SOCKET_FWD:
+		return "socket fwd"
+	}
+	return fmt.Sprintf("socket %d", d-XFRM_SOCKET_IN)
+}
+
+// XfrmPolicyTmpl encapsulates a rule for the base addresses of an ipsec
+// policy. These rules are matched with XfrmState to determine encryption
+// and authentication algorithms.
+type XfrmPolicyTmpl struct {
+	Dst   net.IP
+	Src   net.IP
+	Proto Proto
+	Mode  Mode
+	Spi   int
+	Reqid int
+}
+
+func (t XfrmPolicyTmpl) String() string {
+	return fmt.Sprintf("{Dst: %v, Src: %v, Proto: %s, Mode: %s, Spi: 0x%x, Reqid: 0x%x}",
+		t.Dst, t.Src, t.Proto, t.Mode, t.Spi, t.Reqid)
+}
+
+// XfrmPolicy represents an ipsec policy. It represents the overlay network
+// and has a list of XfrmPolicyTmpls representing the base addresses of
+// the policy.
+type XfrmPolicy struct {
+	Dst      *net.IPNet
+	Src      *net.IPNet
+	Proto    Proto
+	DstPort  int
+	SrcPort  int
+	Dir      Dir
+	Priority int
+	Index    int
+	Mark     *XfrmMark
+	Tmpls    []XfrmPolicyTmpl
+}
+
+func (p XfrmPolicy) String() string {
+	return fmt.Sprintf("{Dst: %v, Src: %v, Proto: %s, DstPort: %d, SrcPort: %d, Dir: %s, Priority: %d, Index: %d, Mark: %s, Tmpls: %s}",
+		p.Dst, p.Src, p.Proto, p.DstPort, p.SrcPort, p.Dir, p.Priority, p.Index, p.Mark, p.Tmpls)
+}