gdk: Filter out either smooth or non-smooth event depending on the evmask

gdk: Filter out either smooth or non-smooth event depending on the evmask

If a device provides both smooth and non-smooth events, the latter will be
flagged with _gdk_event_set_pointer_emulated() so the client side window
receives one or the other. If a device is only able to deliver non-smooth
events, those will be sent, so both direction/deltas may need to be handled.