mdns: Make fuzzer layers compatible with llvm>=6

* Original commit: espressif/esp-idf@1882cbe44e

components/mdns/test_afl_fuzz_host/esp32_mock.h

@@ -1,16 +1,8 @@
-// Copyright 2015-2016 Espressif Systems (Shanghai) PTE 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.
+/*
+ * SPDX-FileCopyrightText: 2015-2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
 #ifndef _ESP32_COMPAT_H_
 #define _ESP32_COMPAT_H_
 
@@ -20,6 +12,7 @@
 #define _ESP_TASK_H_
 
 #ifdef USE_BSD_STRING
+#include <features.h>
 #include <bsd/string.h>
 #endif
 #include <stdint.h>