os_aio_simulated_handle(): Temporarily disable os_file_check_page_trailers(),
which cannot be invoked on compressed pages.

dict_table_add_system_columns(): New function, split from
dict_table_add_to_cache().

mlog_parse_index(): Add system columns to the dummy table and identify
DB_TRX_ID and DB_ROLL_PTR in the dummy index.

buf_LRU_get_free_block(): Note that page_zip->data should be allocated from
an aligned memory pool.

buf_flush_buffered_writes(): Write compressed pages to disk.

buf_flush_post_to_doublewrite_buf(): Copy compressed pages to the
doublewrite buffer.  Zero fill any excess space.

buf_flush_init_for_writing(): Treat all compressed pages the same.

buf_read_page_low(): Read compressed pages from disk.

buf_page_io_complete(): Process compressed pages.

trx_sys_doublewrite_init_or_restore_page(): Process compressed pages.

mlog_write_initial_log_record_fast(): Enable a debug printout
#ifdef UNIV_LOG_DEBUG.

fsp_header_init(), fsp_fill_free_list(): Pass the compressed page size
to buf_page_create().

page_zip_compress_write_log(): Flatten the if-else if-else logic.

page_zip_parse_write_blob_ptr(): Do not test page_zip if page==NULL.

page_zip_parse_write_node_ptr(): Do not test page_zip if page==NULL.
Invoke mlog_close() correctly.

row_sel_store_row_id_to_prebuilt(): Add UNIV_UNLIKELY hint to an
assertion-like test.