Adjust the definition of `target_family`
Adjust the definition of `target_family`

This generalizes the `target_family` to allow it being specified more
than once and apply to other properties than just the operating system
family.

Of particular interest is an ability to match architectures that are a
part of a family of architecutes (e.g. various versions of ARM, WASM or
other targets)

rust-lang/reference,rust-lang/reference