remove unused variable

src/users/log_user_stat.hpp

@@ -12,7 +12,6 @@ struct BehaviorStat {
     shared_ptr <Job> job;
     std::string behavior_name;
     long time_delayed;
-    double submission_time;
 
     BehaviorStat(shared_ptr <Job> job,
                  std::string behavior_name, long time_delayed);