Slow EULA display patch

[Dan Kegel]

Krzysztof wrote:
>Well, *great* to see that solved in the Wine core, but I still think I
>have a bug in RichEdit, because the original (native) riched20 works
>fast, despite the bug you just fixed.

Is there a good test document for which our riched20 is
(with Dan H's patch) still way too slow?  If so, let's dig into this.

FWIW, Dan H also explored a change to make a riched "run" struct be
refcounted; that gave a 4x speedup.  Then he switched to using
git bisect to find the cause of the regression, and shelved the
refcounting patch.
- Dan