build: Install libraries in an arch sub-folder

[Steelskin]

This is the proper installation scheme for Swift libraries and prevents having to manually copy them in build.ps1.

[Steelskin]

@swift-ci please test

[finagolfin]

I tried to implement this years ago, swiftlang/swift#63645, but was told that it was preferred to switch to a whole new triple-named resource directory scheme, so this approach was rejected. Would you and @compnerd be interested in collaborating on switching Swift resource directories to that, ie usr/lib/swift/android/aarch64/ would transition to usr/lib/swift/aarch64-linux-android/? I don't think it's too much work, the main issue is settling on what triples to use.

[Steelskin]

I tried to implement this years ago, swiftlang/swift#63645, but was told that it was preferred to switch to a whole new triple-named resource directory scheme, so this approach was rejected. Would you and @compnerd be interested in collaborating on switching Swift resource directories to that, ie usr/lib/swift/android/aarch64/ would transition to usr/lib/swift/aarch64-linux-android/? I don't think it's too much work, the main issue is settling on what triples to use.

Thanks for the context. It would be great if we could talk more offline about this. I do not have a strong feeling on which directory is better but changing to a triple would be a large change for the Windows installer - and I believe there are some swift-driver changes involves too.

In the meantime, I can add a toggle for this so it only takes effect for the Windows build. WDYT?

[finagolfin]

Sure, I think Saleem switched Windows to this approach a long time ago, but when I tried to do the same with Unix, that wasn't accepted.

Note that I'm not against this approach, particularly since I pushed it in the past myself, just pointing out that it was blocked before.

Who knows, maybe Evan has since changed his mind? Maybe have Saleem talk to him and see.