protobuf: Add EXTLINK netdevice type

This kind of netdevice will serve for external
links such as venet, macvlan/vlan and etc.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

protobuf/netdev.proto

@@ -4,6 +4,13 @@ enum nd_type {
 	LOOPBACK	= 1;
 	VETH		= 2;
 	TUN		= 3;
+	/*
+	 * External link -- for those CRIU only dumps and restores
+	 * link parameters such as flags, address, MTU, etc. The
+	 * existence of the link on restore should be provided
+	 * by the setup-namespaces script.
+	 */
+	EXTLINK		= 4;
 }
 
 message net_device_entry {