[Linux] Windowed mode resolution size does not initiliase properly in Wayland

See tiny floating window in center. This has been a known issue for a while, and got Wayland support disabled on the flatpak because of it.

In software mode, switching to fullscreen and back puts the window in the correct resolution, but in OpenGL doing this disables floating mode so you end up with the window manager trying to tile SRB2 and completely breaking it in the process. Obviously this bit only applies to tiling window managers so it's more of an aside, but the tiny window problem happens even on GNOME wayland and other proper DEs.

Also see: https://github.com/flathub/org.srb2.SRB2/issues/59

Note: when testing, be sure to set SDL_VIDEODRIVER=wayland to ensure SRB2 is running on native Wayland and not Xwayland.