[jdk17u-dev] RFR: 8318474: Fix memory reporter for thread_count

[Evgeny Ignatenko]

8318474: Fix memory reporter for thread_count

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Commit messages:
 - Backport 0baa9ecd76c9be33a1939e47dcae320bc8b65e96

Changes: https://git.openjdk.org/jdk17u-dev/pull/2085/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2085&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318474
  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2085.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2085/head:pull/2085

PR: https://git.openjdk.org/jdk17u-dev/pull/2085