Fix the building issue when protobuf is enabled.

Fu Juntang

2021-09-01 387fe1dbfffdc3d73cf46f2c054f4d25543c8523

 test_socket/heart_beat.sh

@@ -50,6 +50,16 @@
  close
  ;;

  "test2")
  start_server
   sleep 1
   start_clients
   sleep 5
   kill -15 server_pid
   sleep 2 
   close_clients
  ;;

  "")
   start_server
   sleep 1