with FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID and FIL_PAGE_DATA.  The doublewrite
buffer needs to read the space_id in order to determine the type of the page.
Because FIL_PAGE_TYPE could contain garbage in MySQL/InnoDB 5.0 and earlier
versions, we cannot trust fil_page_get_type().  Instead, we have to always
store the space_id at the same location.  This modification wastes 12 bytes
per compressed BLOB page (1.2% on 1-kilobyte pages).