[Fontconfig] Another proposal for saving custom fonts in fontconfig

[Peng Wu]

Hi,

  Here are more details about this API proposal.

FcCustomFont * FcDirCacheBeginCustomFont(const FcConfig *config, const
FcChar8 *file, const unsigned int index, const FcChar8 *stylename);

FcBool FcCustomFontModifyString(FcCustomFont * customfont,
const FcChar8 *object, const FcChar8 *value);

void FcDirCacheEndCustomFont(FcCustomFont * customfont);

  Feel free to comment it.

Thanks,
  Peng