[jdk16u] RFR: 8259954: gc/shenandoah/mxbeans tests fail with -Xcomp

[Aleksey Shipilev]

This improves Shenandoah tests reliability. Affected tests fail with -Xcomp before the patch, and pass after.

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Commit messages:
 - Backport c3c6662528311d3fd3f29bb0131fc5cfd832183c

Changes: https://git.openjdk.java.net/jdk16u/pull/49/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk16u&pr=49&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8259954
  Stats: 12 lines in 2 files changed: 10 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk16u/pull/49.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk16u pull/49/head:pull/49

PR: https://git.openjdk.java.net/jdk16u/pull/49