file_mask.proto is missing a go_package

[tswast]

https://github.com/google/protobuf/blob/master/src/google/protobuf/field_mask.proto

This file probably needs

option go_package = "github.com/golang/protobuf/ptypes/fieldmask";

I have filed golang/protobuf#226 to track including it in the Go protobuf package.

[tswast]

I am working on writing conformance tests for Go and this is needed (mostly because Go doesn't do really relative imports and the Go protobuf compiler doesn't support compiling to multiple packages golang/protobuf#39)

[anandolee]

Already fixed by
option go_package = "google.golang.org/genproto/protobuf/field_mask;field_mask";