pkg,plugins: update for Result struct Interface index changes

It's a pointer now, so we need to use the helper function to set
the field and also test for nil before accessing it.

plugins/main/bridge/bridge.go

@@ -100,7 +100,7 @@ func calcGateways(result *current.Result, n *NetConf) (*gwInfo, *gwInfo, error)
 		defaultNet.Mask = net.IPMask(defaultNet.IP)
 
 		// All IPs currently refer to the container interface
-		ipc.Interface = 2
+		ipc.Interface = current.Int(2)
 
 		// If not provided, calculate the gateway address corresponding
 		// to the selected IP address