Postfx causes other splitscreen consoles to go black/white
When postfx is being drawn, it has to be scissored to only affect the current console being drawn. Otherwise, a view grid with multiple parallel consoles will not be drawn correctly.
This bug is only present when running with a
viewgrid bigger than 1x1.
Fixed|Renderer|FX: Post-processing causes splitscreen views to go blank
fx::PostProcessing and fx::Resize were overriding the viewport when
drawing the content back to the original target. Now they use the
original viewport and just scale the geometry accordingly.