LU-16634 build: improve checkpatch warnings

LU-16634 build: improve checkpatch warnings

Change checkpatch.pl to allow RETURN/GOTO as "end of switch case".

Improve CERROR/CWARN/LCONSOLE/CDEBUG message checking/warning to
print more useful message style advice than just "think hard".

Allow "DFID|DOSTID" within long error strings without complaint.

Add a spelling.txt rule to warn if version checks are added in a
test for future versions.  This is mostly useful for maintenance
branches when patches are being backported with test cases.

Test-Parameters: trivial
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I1a0d2f839949debf346aa15c65b0f407e0ce7057
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50331
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Oleg Drokin <green@whamcloud.com>