(xfont_driver): Don't include xfont_parse_name and

(xfont_driver): Don't include xfont_parse_name and
xfont_build_name.
(enum xlfd_field_idx): Moved to font.c.
(split_font_name, build_font_name): Likewise.
(build_font_list): Call mfont__parse_name_info_font.
(xfont_open): Call mfont__unparse_name.  Free name.
(xfont_parse_name, xfont_build_name): Moved to font.c
(xft_select): Prototype deleted.
(device_open): Check HAVE_FREETYPE on using mfont__ft_driver.
Call mfont_pase_name.