RFR: 8316958: Add test for unstructured locking [v3]

[David Holmes]

On Thu, 28 Sep 2023 09:14:15 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> In my original lightweight-locking PR, I had a testcase that exercises unstructured locking, which is permitted by the JVM spec, but not generated by javac, and thus not executed anywhere. JITs don't compile unstructured-locked code, therefore any code which attempts this would be slow anyway.
>> 
>> Testing:
>>  - [x] runtime/locking
>
> Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix test ID

Marked as reviewed by dholmes (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/15925#pullrequestreview-1650069516