LU-12885 mdd: clearly name variables for MAY_ flags

LU-12885 mdd: clearly name variables for MAY_ flags

Clearly name variables for MAY_READ, MAY_WRITE, MAY_EXEC to
distinguish it from other "mask" variables.

The kernel VFS silently converts the MAY_READ, MAY_WRITE, and
MAY_EXEC flags to ACL_READ, ACL_WRITE, and ACL_EXECUTE modes for
the on-disk ACLs.  It later also converts from the ACL_* flags
to POSIX rwx bits. Verify that these values are the same.

Test-Parameters: trivial
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Idcd91d4c467c4415f1c67a5081721393cd3ebbe5
Reviewed-on: https://review.whamcloud.com/36520
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Oleg Drokin <green@whamcloud.com>