scene_opengl: Use toAlignedRect for clipping rects rather than rounding
Rounding can cause glitches in certain cases as that may result in missing certain pixels, instead use toAlignedRect so we always include at least the entire clipped area.
Rounding can cause glitches in certain cases as that may result in missing certain pixels, instead use toAlignedRect so we always include at least the entire clipped area.