mdns, dns, dhcp, dhcps: update fuzzer test to work in CI

Closes: IDF-1861 and IDF-1990

components/lwip/test_afl_host/esp_netif_loopback_mock.c

@@ -0,0 +1,35 @@
+// Copyright 2020 Espressif Systems (Shanghai) CO LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "esp_netif_lwip_internal.h"
+
+esp_err_t esp_netif_get_ip_info(esp_netif_t *esp_netif, esp_netif_ip_info_t *ip_info)
+{
+    return ESP_ERR_NOT_SUPPORTED;
+}
+
+esp_err_t esp_netif_dhcpc_get_status(esp_netif_t *esp_netif, esp_netif_dhcp_status_t *status)
+{
+    return ESP_ERR_NOT_SUPPORTED;
+}
+
+const char *esp_netif_get_ifkey(esp_netif_t *esp_netif)
+{
+    return esp_netif->if_key;
+}
+
+esp_err_t esp_netif_get_ip6_linklocal(esp_netif_t *esp_netif, esp_ip6_addr_t *if_ip6)
+{            
+    return ESP_ERR_NOT_SUPPORTED;
+}