bug#33532: 26.1; set-window-configuration does not restore display start

[Juri Linkov]

> But that patch does not address window configurations and states -
> simply because it can't access them.  We need a different solution for
> those.  And it obviously does not handle non-default reverters like
> 'dired'.

What do you think about implementing the same behavior for
markers like it's implemented by 'comint-move-point-for-output'?
I.e. the same way as 'comint-move-point-for-output' moves point
to the end of the output, after erasing the buffer markers could
move their positions towards their previous valid position until
there is enough reverted text that they reach the old position.

This is straightforward to implement.  I see print.c has a question
in the comments:

    case PVEC_MARKER:
      print_c_string ("#<marker ", printcharfun);
      /* Do you think this is necessary?  */
      if (XMARKER (obj)->insertion_type != 0)
        print_c_string ("(moves after insertion) ", printcharfun);

I think this is necessary.  And this 'insertion_type' could also
move after insertion until it reaches its old position in the
reverted buffer.