center remove old shm on start.

lichao

2021-06-03 d89ff0ad812cdf178b911843bc3e8c04b2f00845

 src/exported_symbols

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