bug#43866: 26.3; italian postfix additions

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: rpluim@gmail.com,  43866@debbugs.gnu.org
> Date: Mon, 19 Oct 2020 23:45:48 +0300
> 
> Here's is a working implementation.  It binds all key sequences to the key
> 'C-+' that has the mnemonics of adding a character.  'C-+' is free because
> it can't be used to zoom text since its counterpart key 'C--' is already
> taken to input numeric arguments.  'C-+ C-+' is bound to 'insert-char'
> like the current longer key sequence 'C-x 8 RET' that is hard to type.

The implementation seems to rely on a file in the /usr/include tree
that might not be there.  This is a significant disadvantage, IMO.  It
means that, unlike all other similar facilities in Emacs, this one is
not self-contained.

Is it possible to lift this limitation?