esp_netif: Enable use of the ESP-IDF with a non-LWIP (and non-BSD-style) IP stack.

Note: besides the esp-netif component, this commit also disables
net_sockets.c from mbedtls, which is one of the base components and uses BSD API (not specifically lwIP). This might be refactored to use CONFIG_SUPPORT_BSD_API instead of CONFIG_ESP_NETIF_TCPIP_LWIP
in the future.
It also disables smartconfig_ack.c and wifi_init.c from esp_wifi
component for referencing some lwIP config options (smartconfig_ack.c changes might be also
updated to check CONFIG_SUPPORT_BSD_API)

Merges https://github.com/espressif/esp-idf/pull/5856

components/esp_wifi/src/smartconfig_ack.c

@@ -17,14 +17,17 @@
  * it will use UDP to send 'ACK' to cellphone.
  */
 
-#include <string.h>
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
-#include "lwip/sockets.h"
 #include "esp_netif.h"
 #include "esp_log.h"
 #include "esp_wifi.h"
 #include "esp_event.h"
+
+#if CONFIG_ESP_NETIF_TCPIP_LWIP
+
+#include <string.h>
+#include "lwip/sockets.h"
 #include "esp_smartconfig.h"
 #include "smartconfig_ack.h"
 
@@ -208,3 +211,6 @@ void sc_send_ack_stop(void)
 {
     s_sc_ack_send = false;
 }
+
+#endif
+