Ignore unused-variable warning for internal_posix_time variable

  Otherwise in combination with -Werror=all used in newer ESP32 cores will trigger a compilation error.

Author: pennam

src/ArduinoIoTCloudTCP.cpp

@@ -387,7 +387,10 @@ ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_ConnectPhy()
 
 ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_SyncTime()
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
   unsigned long const internal_posix_time = _time_service.getTime();
+#pragma GCC diagnostic pop
   DEBUG_VERBOSE("ArduinoIoTCloudTCP::%s internal clock configured to posix timestamp %d", __FUNCTION__, internal_posix_time);
   return State::ConnectMqttBroker;
 }