[WIP] Build aarch64 wheels

[effigies]

Trying to track down a bug in a library on ARM64, I'm looking to add an ARM64 build to my Travis config (nipy/nibabel#862). We're not currently set up to build numpy from source, so I'm fiddling to see how easy it is to start building wheels here.

[charris]

I'm fiddling to see how easy it is to start building wheels here.

That's fine. We have found it handy for this sort of thing to comment out all the unrelated builds, including in appveyor.

[effigies]

Good call. Next commit will do that.

Assuming this goes reasonably, any objections to adding ppc64le and s390x? Probably separate PRs to keep things focused.

[mattip]

The tricky bit to make these official wheels is to get the build scripts to use the proper OpenBLAS libs. This would need numpy/numpy#15279, which is waiting on a decision about which version of OpenBLAS we should be using: 0.3.7 or 0.3.8dev.

[effigies]

Ah. Looks like this is premature, then. I'll leave it as is for now, to not clog up the CI. Feel free to close, if somebody else (who knows what they're doing...) wants to do this once the OpenBLAS issues are resolved. Otherwise, I'll watch that conversation and return to this once it seems like it's possible to move forward.

[mattip]

Closing in favor of gh-70. Thanks, please continue to find ways to contribute.