feat(lwip): Add <netinet/in.h> header file

components/lwip/port/esp8266/include/netinet/in.h

@@ -0,0 +1,22 @@
+// Copyright 2018-2019 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.
+
+#ifndef IN_H_
+#define IN_H_
+
+#include "lwip/inet.h"
+
+#define IN6_IS_ADDR_MULTICAST(a)    IN_MULTICAST(a)
+
+#endif /* IN_H_ */