[Fontconfig] Patch: prefer cache files in /var/cache/fontconfig over <dir>/fonts.cache-2

[Patrick Lam]

Mike FABIAN wrote:
> We think it is better to prefer the caches in /var/cache/fontconfig
> because the directories where the fonts are (e.g. /usr/share/fonts)
> might be mounted readonly, maybe from some server via NFS.

This sounds sensible to me.  I originally made it read the fonts
directory first because that was the inverse of the order in which it
tries to write, but there's no good reason to invert the order here, and
/var/cache/fontconfig seems more likely to be correct, especially since
it's the first place that fc-cache tries to write to!  I've committed
the patch.

pat