`protoc` is an executable from the `protobuf` formula. How should that be handled? 

I can tell `protoc` to use `bin/"protoc-gen-nanopb"` as plugin, but how should I run `protoc`? Just assuming it will be in `$PATH`, with `Formula["protobuf"].bin/"protoc"` (which feels kind of hacky to me…) or is there a better way?