[triplets][osx] add support for arm64 'apple silicon'

[eklipse2k8]

This adds baseline support for building on arm64 "apple silicon" macs

• What does your PR fix? Fixes Add arm64-osx triplet  #12258

• Does your PR follow the maintainer guide?
  YES

[past-due]

Since Apple has announced they will be transitioning all Macs to Apple Silicon, I think this triplet would merit "official" status. (Or, in the event that a universal multi-arch Mac triplet is doable, said triplet that supports arm64 should merit "official" status.) IMHO.

[cenit]

I think it should be important to be aggressive on this side and quick start ASAP to fix libraries for arm64-osx

By the way, OSX too is deprecated, so maybe it can be arm64-macos. BigSur will be macOS 11.0, after what, 20 years of OSX (meaning v10.x, since the naming change already happened few years ago to macOS)?

[ras0219-msft]

We do plan to make this an official triplet, however we do not want to add it to the official list until we have support in CI.

If you'd like to modify this PR to add it to the community list we can merge it now, otherwise we can leave this open until we get CI support.

[ras0219]

LGTM, is this ready for merging?

[cenit]

Is it really ok to use osx in the name? I know it might break more than expected (it’s not only cosmetic), but it’s not osx anymore for sure when targeting arm64...
(It’s not osTEN... it’s eleven!)

[eklipse2k8]

Is it really ok to use osx in the name? I know it might break more than expected (it’s not only cosmetic), but it’s not osx anymore for sure when targeting arm64...
(It’s not osTEN... it’s eleven!)

@cenit I know you're trying to be pedantic here, but I think switching osx to macos might break automated tools that depend on the original naming. For now I think it should align with the x64 name, and that today is osx.

I agree though that once they make it an official triplet, it might be worth forking to macos at that point and should be a separate PR.

[eklipse2k8]

LGTM, is this ready for merging?

@ras0219 yes! Go for it!

[ras0219-msft]

Thanks!

For now I think it should align with the x64 name, and that today is osx. I agree though that once they make it an official triplet, it might be worth forking to macos at that point and should be a separate PR.

For posterity, this is our thinking as well.

[cenit]

Is it really ok to use osx in the name? I know it might break more than expected (it’s not only cosmetic), but it’s not osx anymore for sure when targeting arm64...

(It’s not osTEN... it’s eleven!)

@cenit I know you're trying to be pedantic here, but I think switching osx to macos might break automated tools that depend on the original naming. For now I think it should align with the x64 name, and that today is osx.

I agree though that once they make it an official triplet, it might be worth forking to macos at that point and should be a separate PR.

You are right, too.
There are many references to OSX in vcpkg. That’s better left for another PR, especially considering this triplet will be unofficial for now