Make changes so that when the diff is done between 'expected' and 'results',

Make changes so that when the diff is done between 'expected' and 'results',
if an operating specific expected file exists, use that for the comparison.
This allows for "legit" differences between results, like the "Result too
large" message vs "Math result not representable" ...

Also, have the failed diffs get output to regression.diffs so that its easy to
view those tests that failed