include/netinet/tcp.h: wrap lwip/tcp.h header for compatibility

Some applications (i.e. Azure IoT SDK) are expecting this header to
exist and to contain the tcp constants and description.

The esp32 did not wrap the lwip/tcp.h header, thus this commit adds a
compatibility layer.

Signed-off-by: Francesco Giancane <francesco.giancane@accenture.com>

Merges https://github.com/espressif/esp-idf/pull/4637

components/lwip/port/esp32/include/netinet/tcp.h

@@ -0,0 +1,21 @@
+// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+// Copyright 2020 Francesco Giancane <francesco.giancane@accenture.com>
+//
+// 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 _NETINET_TCP_H 
+#define _NETINET_TCP_H 
+
+#include "lwip/tcp.h"
+
+#endif /* _NETINET_TCP_H  */