ipv4: use socket option consts from x/sys/unix on zos

Use the socket option constants defined in the golang.org/x/sys/unix
package instead of duplicating them in this package.

Change-Id: I737c5b391ec20cf6ffc791cd713c3653d38e75f5
Reviewed-on: https://go-review.googlesource.com/c/net/+/304713
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/ipv4/control_zos.go b/ipv4/control_zos.go
index 0442000..de11c42 100644
--- a/ipv4/control_zos.go
+++ b/ipv4/control_zos.go
@@ -10,11 +10,13 @@
 
 	"golang.org/x/net/internal/iana"
 	"golang.org/x/net/internal/socket"
+
+	"golang.org/x/sys/unix"
 )
 
 func marshalPacketInfo(b []byte, cm *ControlMessage) []byte {
 	m := socket.ControlMessage(b)
-	m.MarshalHeader(iana.ProtocolIP, sysIP_PKTINFO, sizeofInetPktinfo)
+	m.MarshalHeader(iana.ProtocolIP, unix.IP_PKTINFO, sizeofInetPktinfo)
 	if cm != nil {
 		pi := (*inetPktinfo)(unsafe.Pointer(&m.Data(sizeofInetPktinfo)[0]))
 		if ip := cm.Src.To4(); ip != nil {
diff --git a/ipv4/sys_zos.go b/ipv4/sys_zos.go
index 7426606..be20640 100644
--- a/ipv4/sys_zos.go
+++ b/ipv4/sys_zos.go
@@ -11,24 +11,26 @@
 
 	"golang.org/x/net/internal/iana"
 	"golang.org/x/net/internal/socket"
+
+	"golang.org/x/sys/unix"
 )
 
 var (
 	ctlOpts = [ctlMax]ctlOpt{
-		ctlPacketInfo: {sysIP_PKTINFO, sizeofInetPktinfo, marshalPacketInfo, parsePacketInfo},
+		ctlPacketInfo: {unix.IP_PKTINFO, sizeofInetPktinfo, marshalPacketInfo, parsePacketInfo},
 	}
 
 	sockOpts = map[int]*sockOpt{
-		ssoMulticastTTL:       {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_TTL, Len: 1}},
-		ssoMulticastInterface: {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_IF, Len: 4}},
-		ssoMulticastLoopback:  {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_LOOP, Len: 1}},
-		ssoPacketInfo:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_RECVPKTINFO, Len: 4}},
-		ssoJoinGroup:          {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_JOIN_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq},
-		ssoLeaveGroup:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_LEAVE_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq},
-		ssoJoinSourceGroup:    {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_JOIN_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
-		ssoLeaveSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_LEAVE_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
-		ssoBlockSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_BLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
-		ssoUnblockSourceGroup: {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_UNBLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
+		ssoMulticastTTL:       {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_TTL, Len: 1}},
+		ssoMulticastInterface: {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_IF, Len: 4}},
+		ssoMulticastLoopback:  {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_LOOP, Len: 1}},
+		ssoPacketInfo:         {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_RECVPKTINFO, Len: 4}},
+		ssoJoinGroup:          {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_JOIN_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq},
+		ssoLeaveGroup:         {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_LEAVE_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq},
+		ssoJoinSourceGroup:    {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_JOIN_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
+		ssoLeaveSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_LEAVE_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
+		ssoBlockSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_BLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
+		ssoUnblockSourceGroup: {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_UNBLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
 	}
 )
 
diff --git a/ipv4/zsys_zos_s390x.go b/ipv4/zsys_zos_s390x.go
index 4bbfda0..692abf6 100644
--- a/ipv4/zsys_zos_s390x.go
+++ b/ipv4/zsys_zos_s390x.go
@@ -8,30 +8,6 @@
 package ipv4
 
 const (
-	sysIP_ADD_MEMBERSHIP         = 5
-	sysIP_ADD_SOURCE_MEMBERSHIP  = 12
-	sysIP_BLOCK_SOURCE           = 10
-	sysIP_DEFAULT_MULTICAST_LOOP = 1
-	sysIP_DEFAULT_MULTICAST_TTL  = 1
-	sysIP_DROP_MEMBERSHIP        = 6
-	sysIP_DROP_SOURCE_MEMBERSHIP = 13
-	sysIP_MAX_MEMBERSHIPS        = 20
-	sysIP_MULTICAST_IF           = 7
-	sysIP_MULTICAST_LOOP         = 4
-	sysIP_MULTICAST_TTL          = 3
-	sysIP_OPTIONS                = 1
-	sysIP_PKTINFO                = 101
-	sysIP_RECVPKTINFO            = 102
-	sysIP_TOS                    = 2
-	sysIP_UNBLOCK_SOURCE         = 11
-
-	sysMCAST_JOIN_GROUP         = 40
-	sysMCAST_LEAVE_GROUP        = 41
-	sysMCAST_JOIN_SOURCE_GROUP  = 42
-	sysMCAST_LEAVE_SOURCE_GROUP = 43
-	sysMCAST_BLOCK_SOURCE       = 44
-	sysMCAST_UNBLOCK_SOURCE     = 45
-
 	sizeofIPMreq          = 8
 	sizeofSockaddrInet4   = 16
 	sizeofSockaddrStorage = 128