RFR: 8343724: [PPC64] Disallow OptoScheduling [v2]

[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.

Martin Doerr has updated the pull request incrementally with one additional commit since the last revision:

  Move flag configuration to VM_Version::initialize(). Add EntryAlignment guarantee like on other platforms.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21935/files
  - new: https://git.openjdk.org/jdk/pull/21935/files/a9330b32..db0d279e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21935&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21935&range=00-01

  Stats: 44 lines in 2 files changed: 22 ins; 21 del; 1 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