Basically, we haven't been a good neighbour. Turns out you shouldn't
actually call FcFini when you are done, as some library might still
want to use FontConfig. And they use a shared instance for their
administration.
The idea is that you call FcInit once, and use FcConfigReference
after that to get an instance, you can release. This entry is
ref-counted, and things happen automatically based on that.
At least, I think.
That it works for the version we have packaged it pure coincidence, as that is
one of the few versions that due to a bug allow it. So add the appropriate
template specialisations to support it out-of-the-box within OpenTTD.