(M0_3): Delete it.
(M0): New variable.
(ft_get_charmaps): Refer to M0.
(fc_parse_pattern): Fix previous change.
(ft_list_language): Check also extra chars.
(ft_check_otf): Define it even if HAVE_OTF is undef.
(ft_check_lang): Check the result of FcLangSetHasLang against
FcLangDifferentLang. Check also extra chars.
(ft_list_capability): Delete ifdef HAVE_OTF.
(ft_select): Likewise.
(ft_open): Improve debug information.
(ft_check_capability): New function.
(mfont__ft_driver): Specify ft_check_capability.
(mfont__ft_init): Initialize M0.