RFR: 8319379: G1: gc/logging/TestUnifiedLoggingSwitchStress.java crashes after JDK-8318894

[Albert Mingkun Yang]

Can reproduce the failure using `TEST=gc/logging/TestUnifiedLoggingSwitchStress.java JTREG="REPEAT_COUNT=10"`,  but not any more after the fix.

(The MIN2 was removed as part of JDK-8318894; added back now.)

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Commit messages:
 - g1-age-fix

Changes: https://git.openjdk.org/jdk/pull/16495/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16495&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319379
  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/16495.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16495/head:pull/16495

PR: https://git.openjdk.org/jdk/pull/16495