* Fixed compiler error for av_err2string by redefining in c++ friendly way
* removed link from comment, putting in PR
* fixed formatting
* Minor fix: enable qt gui to find PKG files with lowercase extension .pkg
* Added missing dependencies and instructions for enabling QT for linux builds
Details:
* Switched SDL audio mutex to RW lock. This fixes games that continiously call SetVolume in a different thread (like Ghostbusters)
* Added contition to buffer audio packets independent of video packets. This fixes choppy audio across many games.
* Increased the number of audio frame buffers from 2 to 4. Just in case.
* Migrated to std::jthread and std::mutex from pthreads.
* Fixed a race condition with joins on avplayer close that caused a crash.