Segmentation fault with RoadRunnerSBMLModel

The following results in segmentation faults
```
def test_roadrunnermodel_creation():
    model = RoadrunnerSBMLModel(source=MODEL_REPRESSILATOR)
    assert model
    assert model.sid is None
    assert model.source.source == MODEL_REPRESSILATOR
    assert model.language_type == AbstractModel.LanguageType.SBML
```