Add SerenityOS platform

Find libgl

Add strlcat()

Disable pthread_attr_setschedpolicy()

Use SDL software instead of hardware rendering

Set default options for SerenityOS

Set libretro cores path to /usr/lib/libretro Set video and audio driver to sdl2 Disable vsync The libretro core won't keep running in the background when we are in the menu. Don't pause gameplay when window focus is lost Set some config paths to home directory