a few places accordingly.

os_aio_simulated_handle(): Add TODO comments about skipping the write
checks for compressed pages.

dict_create_sys_tables_tuple(): Write the compressed page size to
the TYPE column.

open_or_create_data_files(): Simplify the fil_node_create() call.

fil_node_create(): Do not touch space->zip_size.  It was already initialized
by fil_space_create().

fil_reset_too_high_lsns(), buf_flush_buffered_writes(): Add TODO comment
about compressed pages.

buf_flush_init_for_writing(): Handle pages of type FIL_PAGE_INODE,
FIL_PAGE_IBUF_BITMAP, and FIL_PAGE_TYPE_FSP_HDR as uncompressed ones.