correct console number for the VT_WAITACTIVE ioctl. Invalid console numbers
caused waiting on an invalid pointer.
Use bcopyw() instead of move_up() and move_down(). bcopyw() handles
overlapped copies and should be faster. Actually use bcopy(). bcopy()
is slightly faster if video memory is 16-bit and about twice as fast if
it is 32-bit. bcopy() is said to fail on someGA's, but syscons already
depends on it working for other accesses to video memory.