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/sockets_ext.h

@@ -0,0 +1,24 @@
+/*
+ * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#pragma once
+#include <stdbool.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define IPV6_MULTICAST_IF    0x300
+#define IPV6_MULTICAST_HOPS  0x301
+#define IPV6_MULTICAST_LOOP  0x302
+
+struct lwip_sock;
+
+bool lwip_setsockopt_impl_ext(struct lwip_sock* sock, int level, int optname, const void *optval, uint32_t optlen, int *err);
+bool lwip_getsockopt_impl_ext(struct lwip_sock* sock, int level, int optname, void *optval, uint32_t *optlen, int *err);
+#ifdef __cplusplus
+}
+#endif