Sccache on macOS

I found that the default caching directories, at https://github.com/travis-ci/travis-build/blob/master/lib/travis/build/script/rust.rb, only work with sccache on Linux, but not macOS. Could someone add the directory $HOME/Library/Caches/Mozilla.sccache to the list of directories cached by default?

I see. It’ll need to vary depending on the OS value.