Merge branch 'feature/sync_ping_v3.1' into 'release/v3.1'

fix(lwip): Fix UDP sync register messsage error (backport v3.1)

See merge request sdk/ESP8266_RTOS_SDK!934

components/lwip/port/esp8266/freertos/udp_sync.c

@@ -256,6 +256,11 @@ void udp_sync_ack_sock(void *in_msg)
     struct api_msg *msg = (struct api_msg *)in_msg;
     struct udp_pcb *pcb = _get_msg_pcb(msg);
 
+    if (UDP_SYNC_NONE == s_msg_type) {
+        TCPIP_APIMSG_ACK(msg);
+        return ;
+    }
+
     ret = _udp_sync_ack_sock_ret(msg, 0);
     if (ret == ERR_OK && _udp_need_proc(pcb)) {
         udp_sync_method_t *method = (udp_sync_method_t *)_udp_priv_data(pcb);

components/lwip/port/esp8266/include/lwipopts.h

@@ -1291,21 +1291,21 @@ size_t memp_malloc_get_size(size_t type);
  * The stack size value itself is platform-dependent, but is passed to
  * sys_thread_new() when the thread is created.
  */
-#define DEFAULT_THREAD_STACKSIZE        0
+#define DEFAULT_THREAD_STACKSIZE        TCPIP_THREAD_STACKSIZE
 
 /**
  * DEFAULT_THREAD_PRIO: The priority assigned to any other lwIP thread.
  * The priority value itself is platform-dependent, but is passed to
  * sys_thread_new() when the thread is created.
  */
-#define DEFAULT_THREAD_PRIO             1
+#define DEFAULT_THREAD_PRIO             TCPIP_THREAD_PRIO
 
 /**
  * DEFAULT_RAW_RECVMBOX_SIZE: The mailbox size for the incoming packets on a
  * NETCONN_RAW. The queue size value itself is platform-dependent, but is passed
  * to sys_mbox_new() when the recvmbox is created.
  */
-#define DEFAULT_RAW_RECVMBOX_SIZE       0
+#define DEFAULT_RAW_RECVMBOX_SIZE       6
 
 /**
  * DEFAULT_UDP_RECVMBOX_SIZE: The mailbox size for the incoming packets on a