backends/native: Translate all coordinates when creating motion event
With commit 7d787688 we switched to storing pointer coordinates in MetaInputDeviceNative instead of ClutterInputDevice, and while we had set the coordinates of the ClutterInputDevice in ClutterStage when queueing an event, we now set the MetaInputDeviceNative coordinates in new_absolute_motion_event().
Here a small mistake snuck in: new_absolute_motion_event() only translates the coordinates of the event, but we call meta_input_device_native_set_coords() using the x and y variables (which remain untranslated), so now the input device coordinates are no longer translated.
Fix that by translating the coordinates we set on the MetaInputDeviceNative, too.
Fixes #1685 (closed)