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

[Lutz Schmidt]

On Wed, 10 Apr 2024 10:03:20 GMT, Amit Kumar <amitkumar at openjdk.org> wrote:

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

LGTM.
It's a trivial change in my opinion: only comment texts are changed. One C++ statement is reformatted.

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Marked as reviewed by lucy (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18710#pullrequestreview-2005145502