Improper locking bugs due to the unreleased locks before program eixt

Hi developers, in the below codes, the lock LOCK_thread_count could be not released before program's exit exit(1);. I think it is better to write pthread_mutex_unlock(&LOCK_thread_count); * before the *exit(1); for better resource management and code symmetry. Thanks!

https://github.com/MariaDB/server/blob/57f14eab20ae2733eb341f3d293515a10a40bc48/storage/maria/unittest/ma_pagecache_single.c#L815-L823