Hi Guix,

I've discovered that our SDL2 unfortunately does not correctly support
Wayland at the moment. I found while running Xonotic I could still kill
the window with xkill, even with the SDL_VIDEODRIVER=wayland variable
set. I unset the DISPLAY variable and tried running it that way and
found that it gave an error and refused to start.

This patch should fix the support. I can now run 'DISPLAY=""
SDL_VIDEODRIVER=wayland xonotic' and it'll run. The window cannot be
killed by xkill, which means it's running Wayland natively.