v1.5.6 breaks 32-bit Windows clang-cl build

[terrelln]

See 94c1020

Reported-by: @georgthegreat

[terrelln]

#3998 works around the issue for clang >= 16, but we still need a fix for older clang versions.

Honestly, we could just drop support for CpuId for older clang versions on Windows, and just return that nothing is supported.

[georgthegreat]

I am OK with dropping older clangs support.

I do not know what chrome and firefox are using, however.

[terrelln]

I am OK with dropping older clangs support.

To be clear, everything would still work, just older compilers wouldn't get opted into code gated by checking the CPUID. So only perf would be impacted.

[Cyan4973]

I wonder if the current code in the dev branch now works fine for this compilation scenario.
Since the issue was published, a few other issues were fixed related to Windows and 32-bit builds.

[georgthegreat]

@Cyan4973, I have imported
283fbd2

to our codebase and the part we do really need (that is core library and zstd cli) compile just fine when targeting windows / clang-cl.