How to enforce unicode font for all charsets?

[Sergey Organov <sorganov@gmail.com>]

Hello,

When there is some particular charset property on text, Emacs chooses
to render it using font that has corresponding encoding, such as:

x:-xos4-terminus-medium-r-normal--24-240-72-72-c-120-microsoft-cp1251

for windows-1251 charset.

When there is no charset property, the font being used to display the
same character is:

xft:-PfEd-DejaVu Sans Mono-normal-normal-normal-*-23-*-*-*-m-0-iso10646-1

I'd like the latter font to be always used, no matter if and what charset
property is active. How do I achieve this goal?

GNU Emacs 26.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.5) of
2019-09-23, modified by Debian

-- Sergey