that will require complete index information.

dict_create_index_step(): invoke dict_index_add_to_cache() before btr_create()

dict_index_remove_from_cache(): make public

dict_index_get_if_in_cache_low(): new function, for holding dict_sys->mutex

buf_flush_init_for_writing(): remove the temporary hook to page_zip_compress()

page_create(): add temporary hook to page_zip_compress()