RFR: 8364822: Comment cleanup, stale references to closeDescriptors and UNIXProcess.c

[Guanqiang Han]

Clean up some stale comment references.  Trivial changes.

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Commit messages:
 - clean up some stale comment references

Changes: https://git.openjdk.org/jdk/pull/26667/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26667&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364822
  Stats: 7 lines in 4 files changed: 0 ins; 3 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/26667.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26667/head:pull/26667

PR: https://git.openjdk.org/jdk/pull/26667