(strnlen): Separated to sysdep.h; include sysdep.h instead.

(strnlen): Separated to sysdep.h; include sysdep.h instead.
(CHISE_Attribute_Table_open): Renamed from
`chise_open_attribute_table'.
(CHISE_Attribute_Table_close): Renamed from
`chise_close_attribute_table'.
(chise_attribute_table_get): Renamed from `chise_get_attribute_table'.
(chise_attribute_table_put): Renamed from `chise_put_attribute_table'.
(CHISE_DS_open): Renamed from `chise_open_data_source'.
(CHISE_DS_close): Renamed from `chise_ds_close'.
(chise_feature_setup_db): New function.
(chise_char_load_feature_value): Use `chise_feature_setup_db'.
(chise_char_gets_feature_value): Likewise.
(chise_char_feature_value_iterate): Likewise.