RFR: 8313785: Fix -Wconversion warnings in prims code [v2]

[David Holmes]

On Sat, 5 Aug 2023 16:21:57 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> This patch fixes Wconversion in code in the src/hotspot/share/prims directory.  Most of the changes correct the types.  jfieldID's are created with the int offset returned by InstanceKlass::field_offset().
>>      int     field_offset      (int index) const { return field(index).offset(); }
>> 
>> So when we get the field offset back, it's an int.
>> 
>> Also stackwalker passes jlong, so made that consistent.
>> 
>> Tested with tier1 on Oracle supported platforms.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Dean's suggested changes.

Generally seems okay. However I don't think the stackwalk changes to use `jlong` are necessary or desirable: it seems a bug to me that the `mode` field is declared as `long` at the Java level, when it is always assigned from an int AFAICS.

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PR Review: https://git.openjdk.org/jdk/pull/15160#pullrequestreview-1564578956