Actually pass custom headers to TCP dial config

psiphon/tunnel.go

@@ -558,6 +558,7 @@ func dialSsh(
 	// Create the base transport: meek or direct connection
 	dialConfig := &DialConfig{
 		UpstreamProxyUrl:              config.UpstreamProxyUrl,
+		UpstreamProxyCustomHeaders:    config.UpstreamProxyCustomHeaders,
 		ConnectTimeout:                time.Duration(*config.TunnelConnectTimeoutSeconds) * time.Second,
 		PendingConns:                  pendingConns,
 		DeviceBinder:                  config.DeviceBinder,