[Fontconfig] blacklisting doesn't work

[Patrick Lam]

Matthias Clasen wrote:
> And the Hershey fonts were still there. It took me quite a while
> to figure out that I need to strip the escapes out of the fc-list 
> output to give the patterns a chance to work. Is that escaping 
> really necessary ? It is certainly confusing...

I think that FcNameUnparse had better escape, but fc-list shouldn't
escape.  So I made FcNameUnparseEscaped which will print out font info
with or without escaping.  I'll commit that this evening, if there are
no objections.

> Anyway, after stripping the escapes out of the patterns, the
> Hershey fonts still would not vanish. I finally came to the 
> conclusion that something like the patch below will be necessary
> to make blacklisting work again.

I think that's correct, we've got to filter the patterns at some point.
 I'll look at that patch again this evening, but will probably commit it.

pat