wifi: fixed missing c++ guards

Closes https://github.com/espressif/esp-idf/issues/4497

components/esp_wifi/include/esp_wifi_default.h

@@ -15,6 +15,10 @@
 #ifndef _ESP_WIFI_DEFAULT_H
 #define _ESP_WIFI_DEFAULT_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * @brief Attaches wifi station interface to supplied netif
  *
@@ -95,4 +99,8 @@ esp_netif_t* esp_netif_create_default_wifi_sta(void);
  */
 esp_err_t esp_netif_create_default_wifi_mesh_netifs(esp_netif_t **p_netif_sta, esp_netif_t **p_netif_ap);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif //_ESP_WIFI_DEFAULT_H

components/esp_wifi/include/esp_wifi_netif.h

@@ -15,6 +15,10 @@
 #ifndef _ESP_WIFI_NETIF_H
 #define _ESP_WIFI_NETIF_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * @brief Number of WiFi interfaces used by wifi-netif abstraction
  */
@@ -80,5 +84,8 @@ bool esp_wifi_is_if_ready_when_started(wifi_netif_driver_t ifx);
  */
 esp_err_t esp_wifi_register_if_rxcb(wifi_netif_driver_t ifx, esp_netif_receive_t fn, void * arg);
 
+#ifdef __cplusplus
+}
+#endif
 
 #endif //_ESP_WIFI_NETIF_H