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

examples/protocols/http_server/advanced_tests/main/main.c

@@ -41,7 +41,7 @@ static void connect_handler(void* arg, esp_event_base_t event_base,
     }
 }
 
-void app_main()
+void app_main(void)
 {
     static httpd_handle_t server = NULL;
 

examples/protocols/http_server/advanced_tests/main/tests.c

@@ -270,7 +270,7 @@ static void register_basic_handlers(httpd_handle_t hd)
     ESP_LOGI(TAG, "Success");
 }
 
-static httpd_handle_t test_httpd_start()
+static httpd_handle_t test_httpd_start(void)
 {
     pre_start_mem = esp_get_free_heap_size();
     httpd_handle_t hd;
@@ -299,7 +299,7 @@ static void test_httpd_stop(httpd_handle_t hd)
     ESP_LOGI(TAG, "HTTPD Stop: Current free memory: %d", post_stop_mem);
 }
 
-httpd_handle_t start_tests()
+httpd_handle_t start_tests(void)
 {
     httpd_handle_t hd = test_httpd_start();
     if (hd) {

examples/protocols/http_server/file_serving/main/main.c

@@ -64,7 +64,7 @@ static esp_err_t init_spiffs(void)
  * file_server.c */
 esp_err_t start_file_server(const char *base_path);
 
-void app_main()
+void app_main(void)
 {
     ESP_ERROR_CHECK(nvs_flash_init());
     tcpip_adapter_init();

examples/protocols/http_server/persistent_sockets/main/main.c

@@ -211,7 +211,7 @@ static void connect_handler(void* arg, esp_event_base_t event_base,
 }
 
 
-void app_main()
+void app_main(void)
 {
     static httpd_handle_t server = NULL;
 

examples/protocols/http_server/restful_server/main/esp_rest_main.c

@@ -121,7 +121,7 @@ esp_err_t init_fs(void)
 }
 #endif
 
-void app_main()
+void app_main(void)
 {
     ESP_ERROR_CHECK(nvs_flash_init());
     tcpip_adapter_init();

examples/protocols/http_server/simple/main/main.c

@@ -267,7 +267,7 @@ static void connect_handler(void* arg, esp_event_base_t event_base,
 }
 
 
-void app_main()
+void app_main(void)
 {
     static httpd_handle_t server = NULL;