RFR: 8343724: [PPC64] Disallow OptoScheduling

[Martin Doerr]

Force off OptoScheduling for PPC64. It should be properly maintained before allowing users to switch it on. It's probably not important for this platform. Also see JBS issue for motivation.

-------------

Commit messages:
 - 8343724: [PPC64] Disallow OptoScheduling

Changes: https://git.openjdk.org/jdk/pull/21935/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21935&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343724
  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/21935.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21935/head:pull/21935

PR: https://git.openjdk.org/jdk/pull/21935