RFR: JDK-8308288: Fix xlc17 clang warnings in shared code [v2]

[Phil Race]

On Fri, 26 May 2023 08:31:46 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".
>> Some of those are in shared 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.
>
> JoKern65 has updated the pull request incrementally with one additional commit since the last revision:
> 
>   forgotton _

I am Ok with the client-libs changes here. I did not look at anything else.
So you'll need more approvals before its ready to push.

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Marked as reviewed by prr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/14146#pullrequestreview-1454101589