message: Upgrade Protobuf version
  The commit is based on 3.7.1 with a fix for BUILD file.
  This will allow TensorFlow to build with future Bazel incompatible change:
  --incompatible_new_actions_api
  --incompatible_disable_deprecated_attr_params
diff: @@ -368,12 +368,13 @@ def tf_workspace(path_prefix = "", tf_repo_name = ""):
  },
  )
  + # 5902e759108d14ee8e6b0b07653dac2f4e70ac73 is based on 3.7.1 with a fix for BUILD file.
  PROTOBUF_URLS = [
  - "http://mirror.tensorflow.org/github.com/protocolbuffers/protobuf/archive/v3.6.1.2.tar.gz",
  - "https://github.com/protocolbuffers/protobuf/archive/v3.6.1.2.tar.gz",
  + "http://mirror.tensorflow.org/github.com/protocolbuffers/protobuf/archive/5902e759108d14ee8e6b0b07653dac2f4e70ac73.tar.gz",
  + "https://github.com/protocolbuffers/protobuf/archive/5902e759108d14ee8e6b0b07653dac2f4e70ac73.tar.gz",
  ]
  - PROTOBUF_SHA256 = "2244b0308846bb22b4ff0bcc675e99290ff9f1115553ae9671eba1030af31bc0"
  - PROTOBUF_STRIP_PREFIX = "protobuf-3.6.1.2"
  + PROTOBUF_SHA256 = "1c020fafc84acd235ec81c6aac22d73f23e85a700871466052ff231d69c1b17a"
  + PROTOBUF_STRIP_PREFIX = "protobuf-5902e759108d14ee8e6b0b07653dac2f4e70ac73"
  tf_http_archive(
  name = "protobuf_archive",
  