RFR: 8288000: compiler/loopopts/TestOverUnrolling2.java fails with release VMs

[Jie Fu]

Hi all,

Please review this trivial change which fixes the failure of compiler/loopopts/TestOverUnrolling2.java with release VMs.
Only `-XX:+UnlockDiagnosticVMOptions` is added.

Thanks.
Best regards,
Jie

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Commit messages:
 - 8288000: compiler/loopopts/TestOverUnrolling2.java fails with release VMs

Changes: https://git.openjdk.java.net/jdk/pull/9080/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=9080&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288000
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/9080.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/9080/head:pull/9080

PR: https://git.openjdk.java.net/jdk/pull/9080