jsonpb: Remove Marshaler.EnumsAsString.
jsonpb: Remove Marshaler.EnumsAsString.

This field is deprecated and no longer does anything.

golang/protobuf,trdata/protobuf,fuchsia-mirror/third_party-github.com-golang-protobuf,tamird/protobuf-2,trdata/protobuf,golang/protobuf,aoeu/protobuf,adnaan/protobuf,tamird/protobuf-2,fuchsia-mirror/third_party-github.com-golang-protobuf,skyportsystems/go-protobuf,skyportsystems/go-protobuf