RFR: JDK-8306304: Fix xlc17 clang warnings in ppc and aix code

[Tyler Steele]

On Fri, 12 May 2023 14:07:26 GMT, JoKern65 <duke at openjdk.org> wrote:

>> When using the new xlc17 compiler (based on a recent clang) to build OpenJDk on AIX , we run into various "warnings as errors".
>> Many of those are in the aix or ppc specific codebase and could be addressed by small adjustments.
>> A lot of those changes are in hotspot, some might be somewhere else in the OpenJDK C/C++ code.
>> With this PR we address only the platform dependent code changes.
>
> Thank you for reviewing

Thanks for your PR @JoKern65. I've been wanting to go over the new ibm-clang compiler warnings as well. It would be nice to 'enable warnings as errors' by default after we make the transition.

I'm not sure if it's been mentioned to you already. As I understand it, we usually wait for 2 reviews before proceeding with changes unless they are deemed trivial.

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PR Comment: https://git.openjdk.org/jdk/pull/13953#issuecomment-1545926700