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/protinfo_linux.go

@@ -0,0 +1,74 @@
+package netlink
+
+import (
+	"fmt"
+	"syscall"
+
+	"github.com/vishvananda/netlink/nl"
+)
+
+func LinkGetProtinfo(link Link) (Protinfo, error) {
+	return pkgHandle.LinkGetProtinfo(link)
+}
+
+func (h *Handle) LinkGetProtinfo(link Link) (Protinfo, error) {
+	base := link.Attrs()
+	h.ensureIndex(base)
+	var pi Protinfo
+	req := h.newNetlinkRequest(syscall.RTM_GETLINK, syscall.NLM_F_DUMP)
+	msg := nl.NewIfInfomsg(syscall.AF_BRIDGE)
+	req.AddData(msg)
+	msgs, err := req.Execute(syscall.NETLINK_ROUTE, 0)
+	if err != nil {
+		return pi, err
+	}
+
+	for _, m := range msgs {
+		ans := nl.DeserializeIfInfomsg(m)
+		if int(ans.Index) != base.Index {
+			continue
+		}
+		attrs, err := nl.ParseRouteAttr(m[ans.Len():])
+		if err != nil {
+			return pi, err
+		}
+		for _, attr := range attrs {
+			if attr.Attr.Type != syscall.IFLA_PROTINFO|syscall.NLA_F_NESTED {
+				continue
+			}
+			infos, err := nl.ParseRouteAttr(attr.Value)
+			if err != nil {
+				return pi, err
+			}
+			pi = *parseProtinfo(infos)
+
+			return pi, nil
+		}
+	}
+	return pi, fmt.Errorf("Device with index %d not found", base.Index)
+}
+
+func parseProtinfo(infos []syscall.NetlinkRouteAttr) *Protinfo {
+	var pi Protinfo
+	for _, info := range infos {
+		switch info.Attr.Type {
+		case nl.IFLA_BRPORT_MODE:
+			pi.Hairpin = byteToBool(info.Value[0])
+		case nl.IFLA_BRPORT_GUARD:
+			pi.Guard = byteToBool(info.Value[0])
+		case nl.IFLA_BRPORT_FAST_LEAVE:
+			pi.FastLeave = byteToBool(info.Value[0])
+		case nl.IFLA_BRPORT_PROTECT:
+			pi.RootBlock = byteToBool(info.Value[0])
+		case nl.IFLA_BRPORT_LEARNING:
+			pi.Learning = byteToBool(info.Value[0])
+		case nl.IFLA_BRPORT_UNICAST_FLOOD:
+			pi.Flood = byteToBool(info.Value[0])
+		case nl.IFLA_BRPORT_PROXYARP:
+			pi.ProxyArp = byteToBool(info.Value[0])
+		case nl.IFLA_BRPORT_PROXYARP_WIFI:
+			pi.ProxyArpWiFi = byteToBool(info.Value[0])
+		}
+	}
+	return &pi
+}