RFR: 8362524: Fix confusing but harmless typos in x86 CPU Features

[Kim Barrett]

On Thu, 17 Jul 2025 16:24:43 GMT, Jan Kratochvil <jkratochvil at openjdk.org> wrote:

> The name `DECLARE_CPU_FEATURE_FLAG` is used in all other cases. In `vmStructs_jvmci.cpp` there was no matching `#define`.

Changes requested by kbarrett (Reviewer).

src/hotspot/cpu/x86/vm_version_x86.cpp line 50:

> 48: VM_Version::CpuidInfo VM_Version::_cpuid_info = { 0, };
> 49: 
> 50: #define DECLARE_CPU_FEATURE_FLAG(id, name, bit) name,

I think the "typo" here is in the `#undef` rather than the define.  Calling this `xxx_NAME` seems
appropriate, since it is providing the name for the feature for collection in `_features_names[]`.
Places that are using `xxx_FLAG` are constructing the enumerator for the feature. There is no
requirement that all uses of an X-macro use the same name for the passed in macro, and indeed
it is quite normal to not do so.

-------------

PR Review: https://git.openjdk.org/jdk/pull/26371#pullrequestreview-3031385928
PR Review Comment: https://git.openjdk.org/jdk/pull/26371#discussion_r2214569387