Both the `CctoolsMachO` and `RubyMachO` module implement a common set of
methods that simplify querying `mach_data`. Move these into a shared
module, that gets included after either of these implementations is
loaded and included in `Pathname`.
remove old mach.rb, replace with cctools_mach.rb and prune ELF case
move ArchitectureListExtension to separate file ELF support is
maintained in Linuxbrew