Fix for pointers to auto variables returned from Python wrapper class methods.

The previous implementation was a quick workaround of C++ const references.

Also removed the unused 'borrowed' flag from the Python wrapper of FrsMaterial.

source/blender/freestyle/intern/python/Interface1D/FEdge/BPy_FEdgeSmooth.cpp

@@ -179,9 +179,7 @@ PyDoc_STRVAR(FEdgeSmooth_material_doc,
 
 static PyObject *FEdgeSmooth_material_get(BPy_FEdgeSmooth *self, void *UNUSED(closure))
 {
-	// FIXME frs_material() returns a const reference.
-	FrsMaterial m(self->fes->frs_material());
-	return BPy_FrsMaterial_from_FrsMaterial(m);
+	return BPy_FrsMaterial_from_FrsMaterial(self->fes->frs_material());
 }
 
 PyDoc_STRVAR(FEdgeSmooth_face_mark_doc,