add some tcp code.

lichao

2021-05-25 5d8aa35858eea622e0e8e4a1f111fd408c483a31

 src/exported_symbols

@@ -5,6 +5,7 @@
   BHUnregister;
   BHRegisterTopics;
   BHQueryTopicAddress;
   BHQueryProcs;
   BHSubscribeTopics;
   BHStartWorker;
   BHHeartbeatEasy;