RFR: 8337418: Fix -Wzero-as-null-pointer-constant warnings in prims code

[Kim Barrett]

On Tue, 30 Jul 2024 11:51:37 GMT, Julian Waters <jwaters at openjdk.org> wrote:

>> Now that we have, and are using, `[[noreturn]]` on all platforms, we no longer need that dead code.
>
> I'll admit, I do prefer having a return to end all possible control flows in a non void method, but oh well

I would rather it not look like it can return null (or some other manufactured "default") when it actually can't.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20385#discussion_r1697794269