lwip: Support for linux target

Implement linux port layer and reuse the original FreeRTOS layer
that's compiled and used on linux target as well, by means of FreeRTOS
simulator.

components/lwip/port/include/debug/lwip_debug.h

@@ -0,0 +1,25 @@
+/*
+ * SPDX-FileCopyrightText: 2015-2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+
+#ifndef _LWIP_DEBUG_H
+#define _LWIP_DEBUG_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void dbg_lwip_tcp_pcb_show(void);
+void dbg_lwip_udp_pcb_show(void);
+void dbg_lwip_tcp_rxtx_show(void);
+void dbg_lwip_udp_rxtx_show(void);
+void dbg_lwip_mem_cnt_show(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _LWIP_DEBUG_H