fix memory leak

liuxiaolong

2021-07-20 232227035c8d6a31eaaf193863cbadda949c08fd

 src/exported_symbols

@@ -5,7 +5,9 @@
   BHUnregister;
   BHRegisterTopics;
   BHQueryTopicAddress;
   BHQueryProcs;
   BHSubscribeTopics;
   BHSubscribeNetTopics;
   BHStartWorker;
   BHHeartbeatEasy;
   BHHeartbeat;