There's a circular dependency in this package, it has
golang-google-genproto-dev in Build-Depends, which depends this package
as well.

To break this, we vendor the original protobuf definitions for rpc
functionality, from the following repos and commits:

 https://github.com/grpc/grpc-proto/tree/master/grpc at commit da219ab.
 https://github.com/googleapis/googleapis/tree/master/google/rpc at commit
 ae909b8.


 -- Shengjing Zhu <i@zhsj.me>  Wed, 13 Sep 2017 00:29:14 +0800
