Fixed memory leak in threadpool

[zManu3k]

Transitioning from raw pointers (std::thread*) to std::shared_ptr<std::thread> to fix memory leak (there seems to be nothing that delete the raw ptr after the thread is terminated).

• std::thread objects now are wrapped in std::shared_ptr (so the memory is now automatically managed)
• CreateThread now creates thread using std::make_shared
• AddThread has been modified to accept std::shared_ptr<std::thread> instead of raw pointers

[COM8]

Oh, wow, thanks :D

Nice catch. That's why I started refactoring the thread pool: #1168

I will merge it for the next 1.11.x release. 1.12.0 then will get the fully refactored thread pool once I dealt with the macOS issues in the CI.

[COM8]

Cherry-picked to the 1.11.x branch and will be part of the 1.11.3 release.