(Qja, Qko): Don't make them static.

(Qja, Qko): Don't make them static.
(enum ftfont_cache_for): New enum.
(fc_charset_table): Undo the previous change.
(ftfont_get_latin1_charset): Delete it.
(ftfont_pattern_entity): Check cache by ftfont_lookup_cache.  Set
FONT_SIZE_INDEX of the entity to 0 for a scalable font.  For a
non-scarable font, try to get AVERAGE_WIDTH.
(ftfont_lookup_cache): Argument FOR-FACE is changed to CACHE_FOR.
Change ft_face_cache from a list of a hash-table.  Don't check
`ja' and `ko' adstyle here.
(ftfont_get_fc_charset): Call ftfont_lookup_cache with
FTFONT_CACHE_FOR_CHARET.
(ftfont_get_charset): Undo the previous change.
(ftfont_open): Call ftfont_lookup_cache with
FTFONT_CACHE_FOR_FACE.
(ftfont_close): Likewise.
(ftfont_has_char): Special handling of `ja' and `ko' adstyle.