RFR: 8351149: Remove dead IA32/X32/!AMD64 code blocks after 32-bit x86 removal [v2]

[duke]

On Tue, 28 Oct 2025 11:36:44 GMT, Anton Seoane Ampudia <aseoane at openjdk.org> wrote:

>> This PR carries out cleanup of `IA32`-, `X32`- and `!AMD64`-guarded code blocks after the removal of the 32-bit x86 architecture from HotSpot.
>> 
>> These code blocks are either not needed anymore or the guards redundant.
>> 
>> Please note that this changeset addresses the "complement" of [JDK-8351159](https://github.com/openjdk/jdk/pull/27987). This is to say, this PR targets all directories that are *not* `cpu/x86` and `os_cpu/x86`.
>> 
>> **Testing:** passes tiers 1-3
>
> Anton Seoane Ampudia has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Apply review comments (restore mistakenly cleaned define)

@anton-seoane 
Your change (at version a26d83f936d1abd1b4c5c9da8382bd81f8f7f046) is now ready to be sponsored by a Committer.

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PR Comment: https://git.openjdk.org/jdk/pull/27990#issuecomment-3456303809