EX-8851 lustre: add uncompressed size to compression header

EX-8851 lustre: add uncompressed size to compression header

It's useful to have the uncompressed size of the data in the
compression header.  Also, we have three checksum fields -
compressed, uncompressed, and header, but in practice,
checksumming the compressed data including the header is
enough to cover all of these.

This patch cleans up all of this at the same time.

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: Ie82e0dbe9c862ddc88999b109cea1f27577dbbff
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/53520
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>