RFR: 8334430: Clean up nativeInst_x86.*

[Vladimir Kozlov]

On Tue, 18 Jun 2024 12:25:48 GMT, Julian Waters <jwaters at openjdk.org> wrote:

>> Remove code in `nativeInst_x86.*` added by [JDK-8171008](https://bugs.openjdk.org/browse/JDK-8171008) old JAOTC implementation and currently unused after JAOTC code was removed.
>> Aarch64 code was already removed by an other cleanup [JDK-8333410](https://bugs.openjdk.org/browse/JDK-8333410).
>> 
>> I also removed `NativePopReg` class which was added during initial HotSpot development and never used.
>> 
>> Tested: tier1
>
> Marked as reviewed by jwaters (Committer).

Thank you @TheShermanTanker for review.

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PR Comment: https://git.openjdk.org/jdk/pull/19758#issuecomment-2176208666