Custom PPSSPP shaders

[LunaMoo]

@Happy Wong assuming you ment "spline36" - that particular post process shader just looks pretty bad, imo might be even completely broken as to me it does only add ring artifacts, however yeah to even do what it should be doing, it requires native res, that's why you see resolution drop since now all upscaling shaders force it. You will also see this resolution drop with 4xHQ(which for a long time was actually broken as well) and in recently added 5xBR which are designed to do similar things.

Upscaling postprocessing shaders looks best in fully 2D games anyway and there's not much point even trying them in 3D racing games with fast changing graphics.