arm-uwp is being deprecated, arm64-uwp should be promoted to a non-Community triplet

[walbourn]

The ARM32 platform is being actively deprecated. See Microsoft Learn

Currently only arm-uwp is a 'supported' triplet, and arm64-uwp is a community triplet. The arm-uwp triplet support should be retired, and arm64-uwp should be promoted to a non-community triplet.

[walbourn]

At a minimum, I believe arm-uwp needs to be moved to a community triplet and arm64-uwp needs to be made a fully supported triplet.

[autoantwort]

I have created #33485 for that

[walbourn]

The CI build was swapped in #33759

[walbourn]

@BillyONeal

In addition to swapping the CI build, I think we need to add to the arm-* triplets a deprecation message so developers know this is coming.

arm-mingw-dynamic.cmake
arm-mingw-static.cmake
arm-uwp-static-md.cmake
arm-uwp.cmake
arm-windows-static.cmake
arm-windows.cmake

[BillyONeal]

We don't currently have a great mechanism for triplets to say that they are deprecated; is there a similar warning emitted by MSBuild / the build tools / etc. whose wording we should match?

[walbourn]

The only messaging I've seen so far is this:

https://learn.microsoft.com/en-us/windows/arm/arm32-to-arm64

arm32 desktop has never been officially, so it's just arm-uwp that they ever supported.

[BillyONeal]

OK, let me ask around for what the rest of the dev tools are doing on vcsig. (IMO the main place that needs to see a warning consistent with the above are MSBuild customers, as I expect most messages we might emit are likely to be dropped on the floor)