bug#67810: 29.1; fonts use synthetic bold on Linux / pgtk

[Eli Zaretskii <eliz@gnu.org>]

> From: Tim Ruffing <crypto@timruffing.de>
> Cc: 67810@debbugs.gnu.org
> Date: Thu, 14 Dec 2023 10:54:45 +0100
> 
> So I think whether overstriking is performed should ideally be a
> property of the font. Having some variable similar to the existing 
> vertical-centering-font-regexp would be great, and this would also make
> it possible to turn off overstriking globally.
> 
> Do you think that's a reasonable thing to add?

What are the chances of someone wanting to disable this feature only
for some fonts?  If we want to allow disabling it globally, it should
be a simple matter of adding a boolean variable exposed to Lisp, and
then performing this only when the variable doesn't inhibit that.

Adding a font property, or a regexp for matching fonts which are
exempt from this, are by contrast much more complex and require more
changes.  For a feature that was so far requested by a single user,
I'm not sure this is justified.

As for your example: if Doom uses this for icons, why cannot Doom
refrain from using bold face for these cases?