fix: Fixing lots of compilation warnings

- fix(esp8266):
  - Adding includes for missing symbols.
  - Removing unused variables.
  - Skip unsupported packing pragmas.
  - Add rom_functions.h for symbols that come from the ESP ROM. Add attributes on
ets_printf so GCC will check the syntax of the formatting string and types of
the arguments.
  - Add ETS_GPIO_INTR_EN(DIS)ABLE macro.
  - Use gpio_output_conf instead of gpio_output_set.

- fix(freertos):
  - Define functions that are useful.
  - Use correct printf symbols when printing.

- fix(lwip):
  - Ignore the warning in sntp.

- fix(mqtt):
  - `xTicksToWait` is unsigned, can't check for less than zero. Remove
unused variables.

- fix(newlib):
  - `_free_r()` returns `void`, not `void *`.
  - Adding includes for missing symbols.

- fix(ssl):
  - Make sure functions always return a value.

Merges https://github.com/espressif/ESP8266_RTOS_SDK/pull/188

components/esp8266/source/esp_wifi_os_adapter.c

@@ -42,7 +42,7 @@ static void *task_create_wrapper(void *task_func, const char *name, uint32_t sta
     portBASE_TYPE ret;
     xTaskHandle handle;
 
-    ret = xTaskCreate(task_func, (const signed char *)name, stack_depth, param, prio, &handle);
+    ret = xTaskCreate(task_func, name, stack_depth, param, prio, &handle);
 
     return ret == pdPASS ? handle : NULL;
 }
@@ -248,7 +248,7 @@ static uint32_t get_free_heap_size_wrapper(void)
 
 static void *timer_create_wrapper(const char *name, uint32_t period_ticks, bool auto_load, void *arg, void (*cb)(void *timer))
 {
-    return xTimerCreate((const signed char *)name, period_ticks, auto_load, arg, (tmrTIMER_CALLBACK)cb);
+    return xTimerCreate(name, period_ticks, auto_load, arg, (tmrTIMER_CALLBACK)cb);
 }
 
 static void *timer_get_arg_wrapper(void *timer)