Removed some not needed when doing delete thd, which caused warnings about

wrong mutex usage from safe_mutex.
Ensure that LOCK_status is always taken before LOCK_thread_count

sql/log.cc

@@ -9597,9 +9597,7 @@ binlog_background_thread(void *arg __attribute__((unused)))
 
   THD_STAGE_INFO(thd, stage_binlog_stopping_background_thread);
 
-  mysql_mutex_lock(&LOCK_thread_count);
   delete thd;
-  mysql_mutex_unlock(&LOCK_thread_count);
 
   my_thread_end();
 

sql/mysqld.cc

@@ -4630,6 +4630,7 @@ static int init_thread_environment()
   mysql_mutex_init(key_LOCK_global_system_variables,
                    &LOCK_global_system_variables, MY_MUTEX_INIT_FAST);
   mysql_mutex_record_order(&LOCK_active_mi, &LOCK_global_system_variables);
+  mysql_mutex_record_order(&LOCK_status, &LOCK_thread_count);
   mysql_rwlock_init(key_rwlock_LOCK_system_variables_hash,
                     &LOCK_system_variables_hash);
   mysql_mutex_init(key_LOCK_prepared_stmt_count,

sql/rpl_parallel.cc

@@ -1372,10 +1372,11 @@ handle_rpl_parallel_thread(void *arg)
   thd->reset_db(NULL, 0);
   thd_proc_info(thd, "Slave worker thread exiting");
   thd->temporary_tables= 0;
+
   mysql_mutex_lock(&LOCK_thread_count);
-  THD_CHECK_SENTRY(thd);
-  delete thd;
+  thd->unlink();
   mysql_mutex_unlock(&LOCK_thread_count);
+  delete thd;
 
   mysql_mutex_lock(&rpt->LOCK_rpl_thread);
   rpt->running= false;

sql/slave.cc

@@ -311,9 +311,7 @@ handle_slave_init(void *arg __attribute__((unused)))
                       thd->get_stmt_da()->sql_errno(),
                       thd->get_stmt_da()->message());
 
-  mysql_mutex_lock(&LOCK_thread_count);
   delete thd;
-  mysql_mutex_unlock(&LOCK_thread_count);
   thread_safe_decrement32(&service_thread_count);
   signal_thd_deleted();
   my_thread_end();
@@ -4961,8 +4959,9 @@ pthread_handler_t handle_slave_sql(void *arg)
   mysql_mutex_unlock(&LOCK_active_mi);
 
   mysql_mutex_lock(&LOCK_thread_count);
-  delete thd;
+  thd->unlink();
   mysql_mutex_unlock(&LOCK_thread_count);
+  delete thd;
   thread_safe_decrement32(&service_thread_count);
   signal_thd_deleted();