RFR: 8291926: ProblemList multiple tests in -Xcomp mode due to JDK-8291649

[Daniel D. Daugherty]

A trivial fix to ProblemList multiple tests in -Xcomp mode due to JDK-8291649.

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Commit messages:
 - 8291926: ProblemList multiple tests in -Xcomp mode due to JDK-8291649

Changes: https://git.openjdk.org/jdk/pull/9754/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9754&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8291926
  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/9754.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9754/head:pull/9754

PR: https://git.openjdk.org/jdk/pull/9754