[FEATURE]Set up CircleCI compile test on macOS

[mabruzzo]

As an open source project, it sounds like we are entitled to 30,000 CircleCI credits for macOS/Windows each month (in addition to the linux CircleCI credits). I think that translates to roughly 200 build-minutes per month.

That isn't enough to setup CircleCI on Pull Requests, but we could probably schedule a 5-10 minute compile test on the main branch that runs 1-3 times per week (more as an indicator of whether or not a problem has cropped up)