FcConfigGetCacheDirs - return the list of directories searched for cache files
#include <fontconfig/fontconfig.h>
FcStrList * FcConfigGetCacheDirs (const FcConfig *config);
FcConfigGetCacheDirs returns a string list containing all of the
directories that fontconfig will search when attempting to load a cache file
for a font directory. If config is NULL, the current configuration is
used.