Mac OS X 10.13

Here is how 10.4 for Mac OS X is build on Homebrew: https://github.com/Homebrew/homebrew-core/blob/master/Formula/mariadb.rb

Should be quite easy to fix. While at it, please also ask dbart to install proper build dependencies on the Mac OS X builder so that it would at least start, and then ensure that the build completes. Now build fails as cmake is missing: http://buildbot.askmonty.org/buildbot/builders/mac-1012-pkg/builds/4656/steps/compile/logs/stdio

Some notes:

1. I've fixed the ownership of the various homebrew directories (`/usr/local/Homebrew/`, `/usr/local/Cellar`, and other dirs) on the mac-1012 builder so that the admin user can update and install packages via the `brew` command
2. I've run `brew update` and `brew upgrade` to update all installed homebrew packages
3. cmake is installed (and has been for years) at `/usr/local/bin/cmake`, but for some reason buildbot's path according to the build log linked in Otto's comment is only showing "PATH=/usr/bin:/bin", it needs to be set to "/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin", but not sure what needs to be done to enable that as the buildbot user has `/usr/local/bin` in their path by default