[Fontconfig] Improving Latin font selection for CJK locales

[Pat Suwalski]

Qianqian Fang wrote:
> the proposed method sounds quite interesting and useful.
> For font developers, I think it will add the power to fine-tune
> the font selections, particularly for massaging CJK fonts with
> Latin fonts. I would like to give my full support on this effort.

We ran into this exact issue when working on the eeePC.

In the en_US.UTF-8 locale, the latin font was a nicely-hinted DejaVu 
Sans, with properly bitmap-hinted Chinese characters as needed from 
other fonts.

In the zh_TW.UTF-8 and zh_CN.UTF-8 locales, it would always use the 
latin characters from the fonts made for Chinese, which had a rather 
ugly bitmap-hinted serif font.

Using some fontconfig XML hackery, we got it to work nice in most 
applications, but sometimes the ugly latin characters in the Chinese 
fonts still show up.

--Pat