Undeprecate the CONS_CURSORTYPE ioctl. It was "deprecated" in 2001,
but it was actually extended then and it is still used (just once) in
/usr/src by its primary user (vidcontrol), while its replacement is
still not used in /usr/src.

yokota became inactive soon after deprecating CONS_CURSORTYPE (this
was part of a large change to make cursor attributes per-vty).

vidcontrol has incomplete support even for the old ioctl. I will
update it soon. Then there are many broken escape sequences to fix.
This is just to prepare for setting cursor colors using vidcontrol.