bug#49004: Update IRC-related references to point to Libera.Chat

[Eli Zaretskii]

> From: Amin Bandali <bandali@gnu.org>
> Cc: 49004@debbugs.gnu.org,  larsi@gnus.org, "J.P." <jp@neverwas.me>, Philip
>  Kaludercic <philipk@posteo.net>, Tassilo Horn <tsdh@gnu.org>
> Date: Sun, 13 Jun 2021 12:07:13 -0400
> 
> > It's a large patch: is there anything here besides mechanical change
> > of the server address?
> 
> It's a bit large, but it is indeed mostly mechanical replacements.
> I also took the liberty to backport the following tiny and relevant
> changes from the 'master' branch:
> 
> - 
> https://git.savannah.gnu.org/cgit/emacs.git/commit?id=a70a344941713baf08dc0c093bdf25cf36b09858
> - 
> https://git.savannah.gnu.org/cgit/emacs.git/commit?id=86e4d770a833538f3cb711eb42d8fd8d764a4635
> - 
> https://git.savannah.gnu.org/cgit/emacs.git/commit?id=19ef864084c9765b7736851b46dcbcbe3dbfcf27

Then the change is fine by me, of course.

Thanks.