fix write taking too long

Author: ficeto

libraries/ESP8266WiFi/src/include/ClientContext.h

@@ -169,6 +169,7 @@ class ClientContext {
 
             _size_sent = will_send;
             DEBUGV(":wr\r\n");
+            tcp_output( _pcb );
             _send_waiting = true;
             delay(5000); // max send timeout
             _send_waiting = false;