Add support for mac arm (m1) runners

[sagudev]

https://github.blog/changelog/2024-01-30-github-actions-introducing-the-new-m1-macos-runner-available-to-open-source/

---

• ./mach build -d does not report any errors
• ./mach test-tidy does not report any errors
• These changes fix #___ (GitHub issue number if applicable)

• There are tests for these changes OR
• These changes do not require tests because ___

[sagudev]

It would be nice if any mac owner could verify that builds work: https://github.com/sagudev/servo/actions/runs/7721819161

[mrobinson]

Question about this: what kind of binary is this building? Isn't it more interesting to build a universal binary for now?

[sagudev]

Currently separate binary per arch, but I expect that we can just do post step that would just join two binaries (no idea if this is even possible, i am not really familiar with macs). As far as I know universal needs to be compiled twice (every time for separate target) and doing natively rather than cross should be better.

[mrobinson]

I'm fairly sure that the binaries we produce right now run just fine on ARM Macs. While a native binary might be nice, is it worth maintaining an entirely new build and then having a complicated step to merge the two binaries? I'm not sure I see the issue with cross-compilation either. What's the concern?

[sagudev]

AFAIK we currently build in CI is for x86 arch and works only due to Rosetta (x86 emulation) on arm macs.

[mrobinson]

It feels like the right thing to do is not to have two builds, but just have proper support for building "fat binaries" on MacOS.

[sagudev]

Even if we build "fat binaries" we would still need to compile twice, so having it seperate will allow as to parallelize this better.

Also joining is indeed possible: https://developer.apple.com/documentation/apple-silicon/building-a-universal-macos-binary

[kklem0]

It would be nice if any mac owner could verify that builds work: https://github.com/sagudev/servo/actions/runs/7721819161

It runs well.
Closing the browser with the close icon on top left freezes the browser, closing through menu works though and I don't think it's the build issue.