RFR: JDK-8318415: Adjust describing comment of os_getChildren after 8315026

[Matthias Baesken]

8315026 adjusted and improved the describings comments already for AIX/Linux. But macOS was not adjusted.

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Commit messages:
 - JDK-8318415

Changes: https://git.openjdk.org/jdk/pull/16236/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16236&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318415
  Stats: 15 lines in 2 files changed: 8 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/16236.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16236/head:pull/16236

PR: https://git.openjdk.org/jdk/pull/16236