RFR: 8377035: [s390x] Disable JSR166 test cases which uses virtual threads [v2]

[Harshit470250]

On Fri, 6 Feb 2026 05:45:09 GMT, Harshit470250 <duke at openjdk.org> wrote:

>> ReentrantReadWriteLock20Test.java is failing on s390 due to virtual threads which are not yet implemented on s390. 
>> SynchronousQueue20Test.java also uses virtual thread so I am also disabling it.
>
> Harshit470250 has updated the pull request incrementally with one additional commit since the last revision:
> 
>   change to use Platform.isS390

`OpenJDK 64-Bit Server VM warning: INFO: os::commit_memory(0x000003efa8500000, 16384, 0) failed; error='Not enough space' (errno=12)`
I will add the failure logs.

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PR Comment: https://git.openjdk.org/jdk/pull/29555#issuecomment-3858212311