Reference import grpc Status to suppress unused errors.

[tamalsaha]

Here is an example proto file that resulted in unused errors:

syntax = "proto3";

package appscode.ci.v1beta1;

option go_package = "v1beta1";

import "google/api/annotations.proto";
import "appscode/api/annotations.proto";

service Metadata {
  rpc ServerInfo(dtypes.VoidRequest) returns (ServerInfoResponse) {
    option (google.api.http) = {
      get : "/ci/v1beta1/metadata/server-info/json"
    };
  }
}

message ServerInfoResponse {
  string provider = 1;
  string server_url = 2;
  string ca_cert = 3;
}

[tamalsaha]

Basically if you have a service that does not use any path/query parameters, this error happens. This bug was introduced in #378

cc: @kazegusuri @tmc

[tmc]

@tamalsaha thanks for the patch.

[tmc]

some files need to be re-generated.

[tamalsaha]

Regenerated example protos