Switch PPC to cross-compilation & testing in emulation

[h-vetinari]

Trying to go back because travis is unstable (often needs many restarts to run through), and to try QEMU 7.

[conda-forge-linter]

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.

[h-vetinari]

Finally there's a QEMU issue for this... https://gitlab.com/qemu-project/qemu/-/issues/1086

[h-vetinari]

@conda-forge-admin, please rerender

[github-actions]

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[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.

[h-vetinari]

@conda-forge/numpy
Amazing news 🤩

After literally years of being unable to run the numpy tests for PPC in emulation due to spurious errors (that didn't appear on native hardware), it looks like the recent QEMU 7.2 has finally gotten rid of those issues (xref this) and we can now treat PPC like aarch here (-> less reliance on flaky Travis).

Planning to merge this change (plus some minor clean-ups) on Sunday.

CC @conda-forge/core

[h-vetinari]

Scipy CI is green as well in emulation 🤯
conda-forge/scipy-feedstock#225

[hmaarrfk]

Just clarifying that qemu 7 is enabled conda forge wide?

[h-vetinari]

Just clarifying that qemu 7 is enabled conda forge wide?

To the best of my understanding, the docker-images always download the latest available qemu-user-static, at least on the x64 agents (which is where we're running this). It might have changed, but I once double-checked this with the image hashes (in the CI log) against those on docker-hub.