examples/rotation: remove unused includes
#include <unistd.h>
#include <wayland-server-core.h>
#include <wlr/backend.h>
-#include <wlr/backend/session.h>
#include <wlr/render/wlr_renderer.h>
#include <wlr/types/wlr_keyboard.h>
#include <wlr/types/wlr_output.h>
-#include <wlr/types/wlr_output_layout.h>
#include <wlr/types/wlr_input_device.h>
#include <wlr/types/wlr_matrix.h>
#include <wlr/util/log.h>
