bug#74861: 31.0.50; etags no longer processing shy groups as expected in --regex options

[Eli Zaretskii]

> Date: Sat, 14 Dec 2024 16:00:24 -0500
> Cc: 74861@debbugs.gnu.org
> From: Daniel Villeneuve <dvilleneuve.4142@gmail.com>
> 
> Thanks for analyzing this.
> This looks like a silent change.
> Maybe etags' documentation should reflect this, as currently the man
> page still says "The syntax of regexps is the same as in emacs."
> which is no longer true.

I've updated the docs to say that shy groups are not supported.

Paul, are there other known differences between glibc/Gnulib regexp
and the Emacs regexp that are worth documenting?