bug#44858: [PATCH] Make byte-compiler warn about wide docstrings

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Thu, 10 Dec 2020 15:53:13 -0600
> Cc: 44858@debbugs.gnu.org
> 
> +(defun internal--fill-string (str)
> +  "Fill string STR to `fill-column'.
> +This is intended for very simple filling while bootstrapping
> +Emacs itself, and does not support all the customization options
> +of fill.el (for example `fill-region')."
> +  (if (< (length str) fill-column)  <<<<<<<<<<<<<<<<<<<<<<<<<

Can we use string-width here instead of length?  If this will work
during bootstrap, it is preferable, I think.