FcCacheNumFont - Returns the number of fonts in cache.
       #include <fontconfig.h>
       int FcCacheNumFont(const FcCache *cache);
       .fi
       This  returns the number of fonts which would be included in the return
       from FcCacheCopySet.
       Fontconfig version 2.8.0
                               18 November 2009              FcCacheNumFont(3)