This makes the cursor pointer held by xf86Cursors.c get reset to NULL
whenever the cursor isn't displayed, and means that the reference
count held in xf86Cursor.c is sufficient to cover the reference in
xf86Cursors.c.

As HideCursor may be called in the cursor loading path after
UseHWCursor or UseHWCursorARGB when HARDWARE_CURSOR_UPDATE_UNHIDDEN
isn't set in the Flags field, the setting of the cursor pointer had to
be moved to the LoadCursor paths.

LoadCursorARGBCheck gets the cursor pointer, but LoadCursorImageCheck
does not. For LoadCursorImageCheck, I added a new function,
xf86CurrentCursor, which returns the current cursor. With this new
function, we can eliminate the cursor pointer from the
xf86CrtcConfigRec, once drivers are converted over to use it.

Signed-off-by: Keith Packard <keithp@keithp.com>
Acked-by: Peter Hutterer <peter.hutterer@who-t.net>