Fail early if licenses cannot be copied from source or URL
Fail early if licenses cannot be copied from source or URL

This prevents us from having the following incorrect behavior (zlib is
just an example):

1. Software `zlib` has missing license files.
2. Build is done and cached
3. We fail at the end of the build with the error
4. Build is restarted without changes. `zlib` is restored from cached
   and post_build wrappers do not run.
5. Licensing checks succeed

rapid7/omnibus,Altiscale/omnibus,rapid7/omnibus,chef/omnibus,DataDog/omnibus-ruby,chef/omnibus,DataDog/omnibus-ruby,rapid7/omnibus,DataDog/omnibus-ruby,chef/omnibus,Altiscale/omnibus,Altiscale/omnibus