Fix possible crash of the test client

The cursor surface is not in the surfaces list when destroyed

Change-Id: Ie29224679776d0abec7862d2976be892c63521a7
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>
Don't include wayland-server.h in public headers

Fix the cmake test

Change-Id: If610b26b43df50c7df4e796e08a16dbf0ba27e5c
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>