[Fontconfig] patch: crosscheck font caches

[Patrick Lam]

John Ellson wrote:
> What about this code in the .spec file of dejavu-fonts-1.15-2 ?
> I can't positively blame this package, but my font problems seemed to
> start about the time I installed it.

Hmm, this looks relatively harmless to me.  But I'll try installing a
couple of fonts packages and seeing if this triggers the problem.

Note that in Mathias Clasen's tarball of broken caches, only the
Japanese fonts had broken caches.  This may or may not be relevant.

pat