Go Ports: Update PG to Ensure Ports Aren't Built if Version Required Not Available

[Christopher Nielsen]

At present, our Go port is pinned at an older version - 1.17.3 - for macOS 10.12 and earlier. With the result being that many Go-based ports simply fail to build for those releases, wasting precious buildbot time.

Just as importantly, the user experience isn’t great, either: There’s no checking what’s supported where, so ports fail to build, with no indication as to why. Instead, we should be informing the user that port xyz isn’t supported on these older releases, if they require a Go version of 1.18+.

While I’m confident we could support the latest version of Go for older macOS releases too, that work hasn’t been done. There’s been discussion related to it here-and-there, and folks have offered helpful suggestions. But little to no tangible progress so far.

In the near term, to both ensure a better user experience - and stop wasting buildbot time - I’d like to see the ‘golang’ portgroup do the right thing. At this point, the check is trivial: If a given port requires Go >= 1.18, and macOS <= 10.12, the port isn’t buildable. Easy-peasy.

Thoughts/concerns?

Cheers,
-Chris