RFR: 8255082: HotSpot Style Guide should permit noexcept

[Kim Barrett]

Please review this change to permit the use of `noexcept` under certain
circumstances in HotSpot code.

http://wg21.link/n3050

Testing:

JDK-8316930 (HotSpot should use noexcept instead of throw()) showed what the
conversion would look like. It will need to be brought up to current mainline,
possibly with modifications.

This is a modification of the Style Guide, so rough consensus among the
HotSpot Group members is required to make this change. Only Group members
should vote for approval (via the github PR), though reasoned objections or
comments from anyone will be considered. A decision on this proposal will not
be made before Friday 16-June-2025 at 12h00 UTC.

Since we're piggybacking on github PRs here, please use the PR review process
to approve (click on Review Changes > Approve), rather than sending a "vote:
yes" email reply that would be normal for a CFV.

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Commit messages:
 - add noexcept

Changes: https://git.openjdk.org/jdk/pull/25574/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25574&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8255082
  Stats: 104 lines in 2 files changed: 104 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/25574.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25574/head:pull/25574

PR: https://git.openjdk.org/jdk/pull/25574