FcConfigAppFontAddFile - Add font file to font database
#include <fontconfig/fontconfig.h>
FcBool FcConfigAppFontAddFile (FcConfig *config, const FcChar8 *file);
Adds an application-specific font to the configuration. Returns FcFalse if the
  fonts cannot be added (due to allocation failure or no fonts found). Otherwise
  returns FcTrue. If config is NULL, the current configuration is used.