Build cpython for Mac OSX ARM64

[nightscape]

I'm not sure if I'm overlooking something, but here's a shot of building cpython for Apple Silicon.
I tried a locally built JAR of this on my MacBook M1 by running the Sample.java file and it correctly printed the formatted date.
@saudet what am I missing? Is it really that easy? 😅

[nightscape]

@saudet I think I missed changing the architecture to arm64 while configureing CPython.
This worked on my machine because that is a native ARM64 M1 chip, but in Github Actions we're cross-building.
Another question that comes to mind is how the cross-building of NumPy itself would work. It cannot use the published arm64 artifact of CPython because that wouldn't run on x86_64.
Did you already solve this in other places?

[saudet]

I used crossenv for that before, but it doesn't work with CPython 3.11.

[nightscape]

Looks like there are more puzzle pieces missing...
python/cpython#23523
Good call in not merging to master 😉
It all seemed too easy 😅

[AutonomicPerfectionist]

@nightscape don't know if you are aware but it seems the recommended procedure for compiling Python on Mac OS is to compile it to a universal2 build, which is a fat build supporting both x86_64 and arm64 Macs. From googling around it seems you can still link to universal2 builds from JNI. Unfortunately I can't test any of this as I don't have a Mac myself, but figured you'd be interested in hearing about it. As for numpy, it seems using crossenv version 1.4 works for Python 11 now, it completes a build for Linux arm without any errors but I have no idea if it works with universal2 builds.

My issue with some info on Linux arm64 builds:

#1381

Issue with some info on compiling Python to universal2:

https://bugs.python.org/issue46749