Minor bugfix to proto_library where some or all language rules would depend on plugins for other languages; e.g.  building the Python protos would need protoc-gen-go.
Minor bugfix to proto_library where some or all language rules would depend on plugins for other languages; e.g.  building the Python protos would need protoc-gen-go.

thought-machine/please,thought-machine/please,thought-machine/please,thought-machine/please,thought-machine/please,thought-machine/please