This cleans up a ton of race conditions, and starts moving towards something
we can use with Clang's -Wthread-safety (but that has a ways to go still).
Simple DirectMedia Layer is a cross-platform development library designed
to provide low level access to audio, keyboard, mouse, joystick, and graphics
hardware via OpenGL and Direct3D. It is used by video playback software,
emulators, and popular games including Valve's award winning catalog
and many Humble Bundle games.
More extensive documentation is available in the docs directory, starting
with README.md. If you are migrating to SDL 3.0 from SDL 2.0,
the changes are extensively documented in README-migration.md.