Mac OS build failing. No error messages but multiple warnings for Apple old code

[native-api]

@rmsharp

I do not think my .travis.yml file has anything that specifies the use of an unsupported OS (EOL)

That’s

The default `osx_image: xcode9.4` is now unusable because MacOS 10.13 is EOL

As of the release of MacOS 11.0 earlier this week, Apple and Homebrew no longer support MacOS 10.13. This means homebrew no longer provides binaries for MacOS 10.13, and on those systems, everything has to be built from source. However osx_image: xcode9.4 is still the default os: osx image. As a result, many jobs fail because they have to start building all the brew packages from source.