
Starting with Xcode 12 Beta 2, builds that used to work on Apple Silicon now break due to `Hardware#oldest_cpu` returning `:nehalem` [1]. This commit is the first in a series of improvements to `Hardware#oldest_cpu`. It resolves the Xcode 12 Beta 2 issue for now. [1]: https://github.com/Homebrew/brew/issues/7857#issuecomment-655536261