* add cursor on/off functions.
* Default cursor state is off (for framebuffer console).
* Turn off cursor in each driver's xxxCursorInit() entrypoint.
* Turn on cursor at the end of each driver's xxxLoadCursor() entrypoint.
works with X11R5 servers shipped with NetBSD 1.3.
Where CACHED_TO_HYS() is still needed for kernel-virtual-to-physical
or physical-to-uncached mapping (fb drivers), replace with
`#include <mips/cpuregs.h>'.
based on "#ifdef MELLON": examine the framebuffer dimensions in the
fb softc, and initialize the x-axis offset appropriately.
User-level changes to (e.g.) an Xserver are still needed to work
on an SFB.