[Fontconfig] Improving Latin font selection for CJK locales

[Ed Trager]

I remember that once upon a time the whole issue of making it possible
for FontConfig to blacklist glyphs from
fonts was discussed.

The idea was that it is easy and fast to write a few lines of XML into
a FontConfig .conf file while it is slow and
laborious to remove glyphs from a font.

Perhaps now is the time to actually implement this functionality in FontConfig?

One group of beneficiaries would be those who want to blacklist LGC
glyphs in existing CJK fonts.

A second group of beneficiaries would be those who wanted to use
certain LGC fonts that are very nice except
for a few characters which they don't like, such as a badly-formed
EURO sign or something like that.  So they
wanted to be able to blacklist just individual bad glyphs in otherwise
"nice" (but probably somewhat older, less-maintained)
fonts.

>
> > I know what I'm about to say is totally silly, but I once managed to
> > achieve what I wanted by deleting the latin characters from the Chinese
> > font altogether.  Then I found a slightly cleaner fontconfig way of
> > doing it.
>
> Actually IMO if the Latin glyph are crappy, removing them is the single
> most correct solution.
>