RFR: 8377035: [s390x] Disable JSR166 test cases which uses virtual threads [v3]

[Harshit470250]

> 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:

  build platform library

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Changes:
  - all: https://git.openjdk.org/jdk/pull/29555/files
  - new: https://git.openjdk.org/jdk/pull/29555/files/746240a7..6ab2d8bf

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29555&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29555&range=01-02

  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/29555.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29555/head:pull/29555

PR: https://git.openjdk.org/jdk/pull/29555