This method takes an optional array of `Pathnames`s or `Strings`s and
extracts the native slice from the specified universal binary. If no
parameter is supplied, this is done on all compatible universal binaries
in a formula's keg.
`deuniversalize_machos` is a no-op on Linux.
I still need to look into a) error handling, and b) whether using this
method requires codesigning on ARM.
I've also added signatures to the methods in `extend/os/linux/formula`.
5e0b786da2