RFR: 8250596: Update remaining manpage references from "OS X" to "macOS"

[Adam Sotona]

Most of the manpages were updated a few years ago but some references remain.
This patch renames remaining references to "macOS".

Please review.

Thanks,
Adam

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Commit messages:
 - 8250596: Update remaining manpage references from "OS X" to "macOS"

Changes: https://git.openjdk.org/jdk/pull/13807/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13807&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8250596
  Stats: 16 lines in 7 files changed: 0 ins; 0 del; 16 mod
  Patch: https://git.openjdk.org/jdk/pull/13807.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13807/head:pull/13807

PR: https://git.openjdk.org/jdk/pull/13807