tools: Mass fixing of empty prototypes (for -Wstrict-prototypes)

* Original commit: espressif/esp-idf@afbaf74007

examples/protocols/asio/chat_server/main/chat_server.cpp

@@ -202,7 +202,7 @@ private:
 
 //----------------------------------------------------------------------
 
-extern "C" void app_main()
+extern "C" void app_main(void)
 {
     ESP_ERROR_CHECK(nvs_flash_init());
     tcpip_adapter_init();