support tcp pub/sub.

lichao

2021-06-30 ae17d1439b35b55212c3a30712e0a60b1d6a99c0

 src/exported_symbols

@@ -7,6 +7,7 @@
   BHQueryTopicAddress;
   BHQueryProcs;
   BHSubscribeTopics;
   BHSubscribeNetTopics;
   BHStartWorker;
   BHHeartbeatEasy;
   BHHeartbeat;