fix(example): included esp_system.h in helloworld example in order to fix warning

examples/get-started/hello_world/main/hello_world_main.c

@@ -11,6 +11,7 @@
 #include "freertos/task.h"
 #include "esp_chip_info.h"
 #include "esp_flash.h"
+#include "esp_system.h"
 
 void app_main(void)
 {

tools/test_apps/system/gdb/main/hello_world_main.c

@@ -10,6 +10,7 @@
 #include "freertos/task.h"
 #include "esp_chip_info.h"
 #include "esp_flash.h"
+#include "esp_system.h"
 
 void app_main(void)
 {