RFR: 8276850: Remove outdated comment in HeapRegionManager::par_iterate

[Thomas Schatzl]

Hi all,

  please review this (trivial?) removal of a hopelessly outdated comment about a method parameter that has not been there for years now...

Testing: gha

Thanks,
  Thomas

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Commit messages:
 - Remove comment

Changes: https://git.openjdk.java.net/jdk/pull/6309/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6309&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8276850
  Stats: 4 lines in 1 file changed: 0 ins; 4 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6309.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6309/head:pull/6309

PR: https://git.openjdk.java.net/jdk/pull/6309