refactor, remove useless code.

lichao

2021-06-01 43d4e95770b0519341153202c9a535aaa8e164c5

 src/exported_symbols

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