remove unused artifacts

sql/event_db_repository.cc:
  remove unused variables - reported by MS compiler
sql/event_queue.cc:
  remove unused variables - reported by MS compiler
sql/event_scheduler.cc:
  remove unused label
sql/events.cc:
  remove unused variable and a label - reported by MS compiler

sql/event_db_repository.cc

@@ -472,10 +472,6 @@ Event_db_repository::open_event_table(THD *thd, enum thr_lock_type lock_type,
 static int
 check_parse_params(THD *thd, Event_parse_data *parse_data)
 {
-  const char *pos= NULL;
-  Item *bad_item;
-  int res;
-
   DBUG_ENTER("check_parse_params");
 
   if (parse_data->check_parse_data(thd))

sql/event_queue.cc

@@ -137,7 +137,6 @@ Event_queue::deinit_mutexes()
 bool
 Event_queue::init_queue(THD *thd, Event_db_repository *db_repo)
 {
-  pthread_t th;
   bool res;
   struct event_queue_param *event_queue_param_value= NULL;
 
@@ -320,9 +319,8 @@ Event_queue::update_event(THD *thd, LEX_STRING dbname, LEX_STRING name,
 void
 Event_queue::drop_event(THD *thd, LEX_STRING dbname, LEX_STRING name)
 {
-  int res;
   DBUG_ENTER("Event_queue::drop_event");
-  DBUG_PRINT("enter", ("thd=0x%lx name=0x%lx", thd, name));
+  DBUG_PRINT("enter", ("thd=0x%lx db=%s name=%s", thd, dbname, name));
 
   LOCK_QUEUE_DATA();
   find_n_remove_event(dbname, name);
@@ -482,8 +480,6 @@ Event_queue::load_events_from_db(THD *thd)
   int ret= -1;
   uint count= 0;
   bool clean_the_queue= TRUE;
-  /* Compile the events on this root but only for syntax check, then discard */
-  MEM_ROOT boot_root;
 
   DBUG_ENTER("Event_queue::load_events_from_db");
   DBUG_PRINT("enter", ("thd=0x%lx", thd));

sql/event_scheduler.cc

@@ -288,7 +288,6 @@ event_worker_thread(void *arg)
     else if (ret == EVEX_MICROSECOND_UNSUP)
       sql_print_information("SCHEDULER: MICROSECOND is not supported");
   }
-end:
   DBUG_PRINT("info", ("BURAN %s.%s is landing!", event->dbname.str,
              event->name.str));
   delete event;

sql/events.cc

@@ -866,7 +866,6 @@ bool
 Events::check_system_tables(THD *thd)
 {
   TABLE_LIST tables;
-  bool not_used;
   Open_tables_state backup;
   bool ret= FALSE;
 
@@ -913,7 +912,6 @@ Events::check_system_tables(THD *thd)
     close_thread_tables(thd);
   }
 
-end:
   thd->restore_backup_open_tables_state(&backup);
 
   DBUG_RETURN(ret);