RFR: 8310813: Simplify and modernize equals, hashCode, and compareTo for BigInteger

[Roger Riggs]

On Fri, 23 Jun 2023 17:27:00 GMT, Pavel Rappo <prappo at openjdk.org> wrote:

> Please review this PR to use modern APIs and language features to simplify equals, hashCode, and compareTo for BigInteger. If you have any performance concerns, please raise them.
> 
> This PR is cherry-picked from a bigger, not-yet-published PR, to test the waters. That latter PR will be published soon.

LGTM; I assume the comment about aarch64 perf was a 10% improvement.

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Marked as reviewed by rriggs (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/14630#pullrequestreview-1505622321