[Accepted in principle] SE-0387: Cross-Compilation Destination Bundles

Great to see this moving forward, thanks to @Max_Desiatov for working on this. I know I had a lot of feedback on this proposal, but I hope to use these bundles for Android, so I'm obsessive about getting it right.

With Swift's extensive cross-compilation support, this feature could really showcase that and differentiate the language moving forward.

Presumably this refers to build-time triples, as this proposal has always supported multiple runtime triples.

This effort inspired me to work on getting runtime libraries for multiple CPU architectures working from a single Swift resource directory by default on non-Darwin/Windows platforms, because it annoyed me that each runtime architecture in a bundle would require a separate resource directory, even though the approach I used was ultimately rejected by the Swift devs. I hope someone works on the alternate approach suggested by them, and we get this fixed.