Fix unfreed memory after cleaning render layers

The freestyle data was never freed when removing a renderlayer.

```
blender -b --factory-startup --debug-memory --python-expr "import bpy;bpy.ops.scene.render_layer_add();bpy.context.scene.render.layers.active_index=0;bpy.ops.scene.render_layer_remove()"
```

source/blender/blenkernel/intern/scene.c

@@ -2052,6 +2052,8 @@ bool BKE_scene_remove_render_layer(Main *bmain, Scene *scene, SceneRenderLayer *
 		return false;
 	}
 
+	BKE_freestyle_config_free(&srl->freestyleConfig);
+
 	BLI_remlink(&scene->r.layers, srl);
 	MEM_freeN(srl);