xfs_scrub: explicitly track corruptions, not just errors

xfs_scrub: explicitly track corruptions, not just errors

Rename the @errors_found variable to @corruptions_found to make it
more explicit that we're tracking fs corruption issues.  Add a new
str_corrupt() function to handle communications that fall under this new
corruption classification.  str_error() now exists to log runtime errors
that do not have an associated errno code.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>