Bugfix - write method of WiFiClient and WiFiClientSecure can stuck forever

Author: dsislak

libraries/ESP8266WiFi/src/include/ClientContext.h

@@ -455,7 +455,7 @@ class ClientContext
                 break;
             }
 
-            ++_send_waiting;
+            _send_waiting = 1;
             esp_yield();
         } while(true);
         _send_waiting = 0;