fix memory leak

liuxiaolong

2021-07-20 13c503b73b4ecc8ce4a6e344f9ac15202985d686

 src/exported_symbols

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