EX-7644 mmap: add mmap support for compression

EX-7644 mmap: add mmap support for compression

This removes the EOPNOTSUPP for compression with mmap and
adds an mmap sanity test for compression.  This patch
removes all the restrictions for mmap, but we actually only
have unaligned read support right now, so the test is
deliberately simplified to only test reads.

A more complicated version which also tests mmap writes
comes later in the series, once read-modify-write is
supported.

The test tests mmap by copying data at several different
block sizes with several different compression chunk sizes.

Test-Parameters: testlist=sanity-compr env=ONLY="1003",ONLY_REPEAT=10
Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: I4a37b106831a903d90e8a8871e9a93baac4e201e
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/52280
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Artem Blagodarenko <ablagodarenko@ddn.com>