Add SDL3

[Ghabry]

To not break too much stuff I suggest to do this in multiple steps:

1. Add SDL3 and keep SDL2 for now. They dont have any file conflicts so this is safe to do
2. Change the default in the Player to SDL3

• For now keep emscripten (canvas scale issues) and Android (crashes) on SDL2

3. When everything is ported remove SDL2 in another PR to buildscripts

[carstene1ns]

We need X11 and/or Wayland packages on Debian and *buntu CI builders:
https://wiki.libsdl.org/SDL3/README-linux#build-dependencies
Or patch it to use -DSDL_UNIX_CONSOLE_BUILD=ON in the yaml.

[Ghabry]

about the build failure on our system: I can either install the packages or pass -DSDL_X11_XSCRNSAVER=OFF -DSDL_X11_XTEST=OFF

XSCRNSAVER is for e.g. disabling screen locking and XTEST for UI automation. Both arent required.

What do you prefer?

[carstene1ns]

Well, if I interpret the output correctly we do not have sound yet anyway. So additional package for e.g. pulse is needed as well. But I also think both extensions are not strictly needed for the build.

[Ghabry]

I'm not sure if this -DCMAKE_PREFIX_PATH=/ is a good way to do it but it adds no additional system libraries to the binary:

        linux-vdso.so.1 (0x00007fd187fbc000)
        libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00007fd186400000)
        libm.so.6 => /usr/lib/libm.so.6 (0x00007fd187e44000)
        libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0x00007fd187e17000)
        libc.so.6 => /usr/lib/libc.so.6 (0x00007fd18620f000)
        /lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2 (0x00007fd187fbe000)

This also looks solid:

-- Enabled backends:
--   Video drivers: dummy offscreen wayland(dynamic) x11(dynamic)
--   X11 libraries: xcursor xdbe xfixes xinput2 xrandr xshape xsync
--   Render drivers: gpu ogl ogl_es2 vulkan
--   GPU drivers: vulkan
--   Audio drivers: alsa(dynamic) disk dummy pipewire(dynamic) pulseaudio(dynamic)
--   Joystick drivers: hidapi linux virtual
--   Camera drivers: dummy pipewire(dynamic) v4l2

[Ghabry]

Another option is unsetting the PKG_CONFIG variables. Gives exactly the same backends:

-- Enabled backends:
--   Video drivers: dummy offscreen wayland(dynamic) x11(dynamic)
--   X11 libraries: xcursor xdbe xfixes xinput2 xrandr xshape xsync
--   Render drivers: gpu ogl ogl_es2 vulkan
--   GPU drivers: vulkan
--   Audio drivers: alsa(dynamic) disk dummy pipewire(dynamic) pulseaudio(dynamic)
--   Joystick drivers: hidapi linux virtual
--   Camera drivers: dummy pipewire(dynamic) v4l2

[carstene1ns]

gogogo