ggiSetSplitline - Set the hardware split line feature
int ggiSetSplitline(ggi_visual_t vis, int y);
Original VGA adaptors in order to be efficient when displaying
vertically scrolling scenery implemented a feature that, when used in
combination with the display origin, could cause the screen to wrap.
This essentially means you can take the framebuffer and seamlessly join
the top edge to the bottom edge, creating a cylinder of data that you
could scroll up or down without actually performing memory move
operations. This functions sets the y coordinate at which the screen
0 for OK, otherwise an ggi-error(3) code.