Mac: Remove universal binary support.

[rryan]

Now that macOS is pretty much all amd64, we don't need to make universal PPC/i386/amd64 builds, so we can remove a bunch of code that supports that.

[Pegasus-RPG]

Up to what age of machines do we want to support?

[Pegasus-RPG]

Can we check the Web logs to get an idea of how many people on non-amd64 Macs visit the site at least? Or do we have metrics of how many non-amd64 ones click the download link?

[Be-ing]

What is the cost of continuing to build universal binaries?

[rryan]

We dropped x86 and PPC support years ago (1.11?), so this is just removing the vestigial code that supported building a single binary for all 3.

[rryan]

We require macOS 10.8, which doesn't support x86 or PPC.

[Be-ing]

Okay, then let's remove the vestigial code 👍

[Pegasus-RPG]

We can always pull it out of the history if we ever need it again, right? If so, go ahead.

[ywwg]

the most likely future scenarios are mac remains 100% x64, or they come out with a line of ARM macs and we need a universal binary that's x64 and ARM

[ywwg]

(further prediction: current macOS libs (carbon/cocoa whatever) will be compatibility mode, and the main UI will move toward iOS-on-desktop)