RFR: JDK-8307810: Consistently use LockingMode instead of UseHeavyMonitors

Wed May 10 11:27:32 UTC 2023

[JDK-8291555](https://bugs.openjdk.org/browse/JDK-8291555) phased out UseHeavyMonitors in favor of LockingMode=0. We forgot to apply these changes to PPC and S390. 

Since UseHeavyMonitors implies LockingMode, but not vice versa, we now have a mismatch if JVM is started with LockingMode=0 but without UseHeavyMonitors. That leads to crashes.

The patch fixes that, and in addition makes sure that if LockingMode=0 is set, we are setting UseHeavyMonitors too.

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Commit messages:
 - JDK-8307810-use-lockingmode-instead-of-useheavymonitors

Changes: https://git.openjdk.org/jdk/pull/13900/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13900&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307810
  Stats: 14 lines in 6 files changed: 4 ins; 0 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/13900.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13900/head:pull/13900

PR: https://git.openjdk.org/jdk/pull/13900