Taps client client for vrtsim

Added a libary that can connect to a channel emulator and provide taps
as they are generated.

 - Enable connection from vrtsim to channel emulation server
 - Depends on flatbuffers definition file from raytracing-channel-emulator
 - Depends on libanomsg-dev and flatbuffers-compiler (Ubuntu) or equivalent
 - Added a compile time option ENABLE_TAPS_CLIENT to prevent other users
   from being affected by additional dependencies

radio/vrtsim/taps_client.h

@@ -0,0 +1,38 @@
+/*
+ * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The OpenAirInterface Software Alliance licenses this file to You under
+ * the OAI Public License, Version 1.1  (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.openairinterface.org/?page_id=698
+ *
+ * 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.
+ *-------------------------------------------------------------------------------
+ * For more information about the OpenAirInterface (OAI) Software Alliance:
+ *      contact@openairinterface.org
+ */
+
+#ifndef TAPS_CLIENT_H
+#define TAPS_CLIENT_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "sim.h"
+
+void taps_client_connect(int id, const char *socket_path, int num_tx_antennas, int num_rx_antennas, channel_desc_t **channel_desc);
+void taps_client_stop();
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif