RFR: 8342924: GenShen: Problem list gc/shenandoah/TestReferenceRefersToShenandoah.java

[William Kemper]

Skip gc/shenandoah/TestReferenceRefersToShenandoah.java while we work on solution.

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Commit messages:
 - Problem list failing reference processing test

Changes: https://git.openjdk.org/shenandoah/pull/525/files
  Webrev: https://webrevs.openjdk.org/?repo=shenandoah&pr=525&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342924
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/shenandoah/pull/525.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/525/head:pull/525

PR: https://git.openjdk.org/shenandoah/pull/525