[lworld] RFR: 8334140: [lworld] -XX:LockingMode=0 ignored makes MapLoops fail

[Roger Riggs]

The MapLoops test uses `-XX:LockingMode=0 -XX:+VerifyHeavyMonitors ` for a debug test run.
However, the LockingMode command line option is overridden in arguments.cpp when 
Valhalla is enabled and it forces the lock mode to be LM_LEGACY.

The default for lightweight locking should only be overridden if Valhalla is enabled.

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Commit messages:
 - 8334140: [lworld] -XX:LockingMode=0 ignored makes MapLoops fail

Changes: https://git.openjdk.org/valhalla/pull/1124/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1124&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8334140
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/valhalla/pull/1124.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1124/head:pull/1124

PR: https://git.openjdk.org/valhalla/pull/1124