Since it's storing an locally defined (ddx-internal) struct, it's better
not to abuse some globally defined key for this.
It just happened to work before, since CursorScreenKey is only used by DDX
(and there's only one DDX per executable) and they currently (!) have the
same size (pointer) - but that's a fragile programming style, so clean it up.
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1342>
49d139344d