RFR: 8294314: Minimize disabled warnings in hotspot [v9]

[Magnus Ihse Bursie]

On Tue, 27 Sep 2022 17:27:30 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Don't need empty-body for ad_ppc.cpp now that it is globally disabled
>
> Related: hopefully eliminating `char-subscripts` warning with #10455.

@shipilev I had hoped this PR would trigger warning hunting in Hotspot, but I did not anticipate that it would happen even before it was pushed! ;-) Let me know when you are done fixing individual warnings; there seem to be little point in integrating this until these fixes has started to slow down.

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PR: https://git.openjdk.org/jdk/pull/10414