Set stdout to unbuffered (#2508)

* Set stdout to unbuffered

This fixes issue #2507 esp32 serial console doesn't show output until
enter pressed.

* Moved setvbuf call to app_main immediately after console_init

components/base_nodemcu/user_main.c

@@ -165,6 +165,7 @@ void app_main (void)
 #endif
 
   console_init (&cfg, input_task);
+  setvbuf(stdout, NULL, _IONBF, 0);
 
   nodemcu_init ();