FcConfigAppFontAddDir - Add fonts from directory to font database
#include <fontconfig/fontconfig.h>
FcBool FcConfigAppFontAddDir (FcConfig *config, const FcChar8 *dir);
Scans the specified directory for fonts, adding each one found to the
application-specific set of fonts. Returns FcFalse if the fonts cannot be
added (due to allocation failure). Otherwise returns FcTrue. If config
is NULL, the current configuration is used.