bug#61514: 30.0.50; sadistically long xml line hangs emacs

[Gregory Heytings]

> > > I don't think we want that for `emacs-29`, but unless there's some 
> > > objection I'll push this to `master`,
> >
> > Assuming all the regex-emacs-tests and search-tests pass after this 
> > change, please install on emacs-29, and thanks.
>
> It passed the tests, I pushed it to `emacs-29`.

Great!  I guess we should we also fix the bug in nXML?