linux-aarch64 + osx-arm64 versions of gdb-multi-arch

[noahp]

For osx-arm64, it looks like we can probably do this with the cross-build instructions here (requires intel mac host, eg the github runner we use):
https://conda-forge.org/blog/posts/2020-10-29-macos-arm64/

Testing would probably require a physical machine though :(

linux-aarch64 should be quite a lot easier:
https://github.com/multiarch/qemu-user-static

[noahp]

Another idea (thanks @alvarop !), rewrite the osx-64 packages as osx-arm64 and let rosetta deal with it.. presumably this works for the dependent packages?? no idea!).

[tyhoff]

I'm working on this btw.