Switch to cross-compilation for linux_aarch64 and linux_ppc64le

[bdice]

This PR switches to cross-compilation for linux_aarch64 and linux_ppc64le.

See conda-forge/cuda-feedstock#25

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[jakirkham]

Thanks Bradley! 🙏

As this package has target_platform in it, am going to take a closer look at this one. From a cursory look it seems ok. Just want to double check

Going to mark as draft for now

[jakirkham]

Have rechecked the meta.yaml and build.sh and compared with the logs to confirm we are seeing behavior we expect for the cross-compiled targets. This looks good