[crac] RFR: Print better diagnostics for spawning CRIU [v4]

[Anton Kozlov]

On Thu, 10 Aug 2023 07:28:29 GMT, Jan Kratochvil <jkratochvil at openjdk.org> wrote:

>> It was always a mystery why it does not work this time as there are no error messages printed.
>> Still may system call errors are currently not reported but those errors at least do not happen commonly.
>> In fact `os::exec_child_process_and_wait` should be more verbose but that is already a part of OpenJDK so I did not modify it.
>> It would be much easier if `criuengine.c` was in C++. I was considering to switch it but then I wrote it already in C.
>> I understand this code will become obsolete after planned integration of CRIU into JVM but it may not yet be soon enough.
>
> Jan Kratochvil has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Reformat error messages
>    - Radim Vansa

Marked as reviewed by akozlov (Lead).

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PR Review: https://git.openjdk.org/crac/pull/97#pullrequestreview-1571714639