remove AtomicQueue, not used.

lichao

2021-06-01 72851db66655912cb9c92300a80985fb9797d168

 src/exported_symbols

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