[lworld] RFR: 8371398: [lworld] runtime/valhalla/inlinetypes/FlatArrayCopyingTest.java#g1 fails due to lack of UnlockDiagnosticVMOptions

[Paul Hübner]

Hi all,

The flag `UnlockDiagnosticVMOptions` should be set explicitly.

Tests: tier 1, tier 5.

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Commit messages:
 - Explicitly enable diagnostic options.

Changes: https://git.openjdk.org/valhalla/pull/1726/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1726&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8371398
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/valhalla/pull/1726.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1726/head:pull/1726

PR: https://git.openjdk.org/valhalla/pull/1726