MetaHookSv-refs/tags/v20240318b

[ThreadGuard] Fixed a bug since v20240314a, that thread termination not being handled correctly on _restart.
[Renderer] Fixed a bug that fog was not working. #424
[Renderer] Fixed an inconsistency about fallback policy when current sky textures are not found between Renderer and vanilla engine. #421

[ThreadGuard] 修复了v20240314a版本之后出现的问题，该问题会导致线程退出的行为在使用_restart重启游戏时没有正确被等待，有可能导致游戏的残留线程在游戏重启后再次得到执行、继而引发游戏崩溃。
[Renderer] 修复了一个fog失效的问题。 #424
[Renderer] 修复了一个加载天空贴图时行为不一致的问题：原版引擎在找不到当前天空对应的天空贴图时会fallback到desert**.tga/desert**.bmp，而Renderer不会。 #421