bug#33871: 27.0.50; Revert Dired window saved in window configuration

[martin rudalics]

> I nowlooked into it.  It's a bug caused by
>
>        XMARKER (p->pointm)->insertion_type
>          = !NILP (buffer_local_value /* Don't signal error if void.  */
>               (Qwindow_point_insertion_type, w->contents));
>
> and the value of
>
> buffer_local_value (Qwindow_point_insertion_type, w->contents)
>
> is unbound and not nil.  I have to fix that.

I tried to fix that on master now.  Please have a look.

Thanks, martin