add safety checks to e_client_focus/raise_latest_set() fns
add safety checks to e_client_focus/raise_latest_set() fns

passing a null client here breaks the universe, so ensure that it's
easily catchable

tasn/enlightenment,tasn/enlightenment,tizenorg/platform.upstream.enlightenment,rvandegrift/e,tizenorg/platform.upstream.enlightenment,rvandegrift/e,tasn/enlightenment,tizenorg/platform.upstream.enlightenment,rvandegrift/e