OpenGL HUD scaling fix
This fixes OpenGL's HUD not placing the Score/Time/Rings stats, as well as other HUD items such as the Race countdown numbers + GO graphics, in the right places on screen in non-green resolutions, compared to Software mode.
Have some images for comparison (both taken in 640x480):
Before fix:
After fix:
I also probably fixed an issue with HUD items using V_SNAPTO* flags combined with the scaling flags, but I haven't tested this out properly yet.