message: Fix copy&paste typo in swWorker_onTask()
  Reference: Coverity CID
diff: @@ -288,7 +288,7 @@ int swWorker_onTask(swFactory *factory, swEventData *task)
  break;
  case SW_EVENT_BUFFER_EMPTY:
  - if (serv->onBufferFull)
  + if (serv->onBufferEmpty)
  {
  serv->onBufferEmpty(serv, &task->info);
  }
  