protobuf_benchmarks: Allow overriding the path to the datasets directory (#693)
protobuf_benchmarks: Allow overriding the path to the datasets directory (#693)


dart-lang/dart-protobuf,dart-lang/dart-protobuf,google/protobuf.dart,dart-lang/protobuf,dart-lang/protobuf,google/protobuf.dart,google/protobuf.dart,dart-lang/dart-protobuf,dart-lang/protobuf