community/sdl: fix patch url, enable tslib
SDL moved to github, see https://discourse.libsdl.org/t/sdl-moving-to-github/28700 breaking a patch url in APKBUILD. Also enable tslib support.
SDL moved to github, see https://discourse.libsdl.org/t/sdl-moving-to-github/28700 breaking a patch url in APKBUILD. Also enable tslib support.