bug#34569: 26.1.90; Zero wide scroll bars

[martin rudalics]

>> But yes: One way to fix the aborts should be to disallow setting the
>> 'scroll-bar-width' frame parameter to zero.
>
> Then I think we should do that.

It means though that we have to do some non-standard surgery in the
frame parameters area.  Note that x_report_frame_params inserts the
zero value automatically via

  store_in_alist (alistptr, Qscroll_bar_width,
                  (! FRAME_HAS_VERTICAL_SCROLL_BARS (f)
                   ? make_fixnum (0)
                   : FRAME_CONFIG_SCROLL_BAR_WIDTH (f) > 0
                   ? make_fixnum (FRAME_CONFIG_SCROLL_BAR_WIDTH (f))
                   /* nil means "use default width"
                      for non-toolkit scroll bar.
                      ruler-mode.el depends on this.  */
                   : Qnil));

What should we use instead?

martin