Add support for stack overflow error regressions

[chrissimpkins]

From a conversation that began in #53 (comment)

It would be helpful to support stack overflow errors as the regression definition. This can be hard coded with the current --regress= definition approach as of #53 , or supported through a new command line option that takes a substring for the stderr message search.

[ehuss]

#142 has changed it so that a stack overflow is treated the same as an ICE.

[ehuss]

I'm going to close as resolved by #142, though please reopen if there is a specific need the --regress option doesn't solve.