input: Don't try to send pointer frames if no focus_client

Prevents a segfault when mousing into clients that don't get_pointer
like weston-simple-shm and weston-simple-damage.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
Reviewed-by: Marek Chalupa <mchqwerty@gmail.com>
1 file changed