glyphs is broken at drawtext filter

[zenix]

Summary of the bug:
glyphs is broken at drawtext filter
when a sentence is mixed other character set
(ex. english+korean)
I ran ffmpeg on windows 10

However I found the solution at libass library
You have to set the substitution font by FcConfigSubstitute function when ffmpeg sets font on drawtext filter.

How to reproduce:

% ffplay -i anything -vf "[in]drawtext=font='Arial':text='ffmpeg 에프에프엠펙'"
ffmpeg version 4.3
built on ... msys2 

Patches should be submitted to the ffmpeg-devel mailing list and not this bug tracker.