[crac] RFR: Implement CRaC exit codes

[Anton Kozlov]

On Mon, 20 Mar 2023 15:08:18 GMT, Roman Marchenko <rmarchenko at openjdk.org> wrote:

> Implement CRaC exit codes in case it catches a signal.
> 
> This is a continuation of #46  inspired by [this comment](https://github.com/openjdk/crac/pull/46#discussion_r1122014722)
> 
> So, in case the child is terminated by a signal, CRaC should be terminated in similar way too, if possible. Otherwise it returns 128+n exit code as bash does.

LGTM, thanks!

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PR: https://git.openjdk.org/crac/pull/52