RFR: 8330011: [s390x] update block-comments to make code consistent

[Amit Kumar]

It doesn't (shouldn't) affect the runtime. So I haven't run any test. But builds I have performed.

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Commit messages:
 - updates block_comments

Changes: https://git.openjdk.org/jdk/pull/18710/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18710&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8330011
  Stats: 27 lines in 2 files changed: 2 ins; 0 del; 25 mod
  Patch: https://git.openjdk.org/jdk/pull/18710.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18710/head:pull/18710

PR: https://git.openjdk.org/jdk/pull/18710