Also remove the tentative way compilation was expected to be fixed on
macOS ARM without really working.
In the future we will create universal binaries (which requires
compiling our prebuilt package for ARM as well), but until then we must
require the developer to pass `--cpu=darwin_x86_64` to the build
command when building on an ARM macOS platform like the M1. This will be
printed out explicitly now if it's not the case.
Alexandre Boulgakov
Nora Dimitrijević
Paolo Tranquilli