fix: loss notify when HThreadPool::stop()

[nijiancong]

原子谓词也可能导致唤醒问题
参考:

1. https://www.modernescpp.com/index.php/c-core-guidelines-be-aware-of-the-traps-of-condition-variables/
2. https://www.cnblogs.com/fenghualong/p/13855360.html