Fix unit specs on Sparc.

Turns out this spec is broken on Sparc. 

```
Error Message

uninitialized constant File::NOFOLLOW
Stacktrace

      uninitialized constant File::NOFOLLOW
/opt/chef/embedded/apps/chef/spec/unit/api_client/registration_spec.rb:215:in `block (4 levels) in <top (required)>'
```

/cc: @lamont-granquist