protoc-gen-go-1.2.0-bp153.1.59

- Make use of tar_scm service.
- Update to version 1.2.0:
  * proto: fix handling of required fields after multiple
    violations (#679)
  * Update issue templates
  * README.md: remove usage of group in example (#673)
  * jsonpb: avoid unexported fields in hand-crafted message (#671)
  * proto: make invalid UTF-8 errors non-fatal (#660)
  * jsonpb: strictly document JSONPBMarshaler and JSONPBUnmarshaler
    behavior (#662)
  * proto: revert strict erroring of deterministic and custom
    marshalers (#658)
  * protoc-gen-go: refactor generator by splitting up
    generateMessage (#657)
  * proto: fix and cleanup test for deterministic marshal with
    custom marshalers (#656)
  * jsonpb: avoid copying string-valued map-keys (#654)
- Add protoc-gen-go-source package - some Go programs using gRPC
  and protobuf need protobuf definitions which are included inside
  the source code.
- Patch protoc-gen-go source to add Bazel support.

- Initial release