(ft_list): Likewise. If FONT is not NULL, check all fonts.
(mfont__ft_init): Initialize above new variables.
(mfont__ft_fini): Free ft_family_list.
+ (STRDUP_LOWER): New macro.
+ (set_font_info): Use STRDUP_LOWER.
+ (ft_list_family): Avoid duplicate addition of font path. Use
+ STRDUP_LOWER.
+ (fc_decode_prop): Fix typo.
* m17n-X.c (MDisplayInfo): New member all_fonts_scaned.
(xfont_registry_list): Change argument disp_info to frame.