sflow: do not handle impossible case where there are not samples
sflow: do not handle impossible case where there are not samples

skydive-project/skydive,lebauce/skydive,lebauce/skydive,lebauce/skydive,lebauce/skydive,lebauce/skydive,skydive-project/skydive,skydive-project/skydive,skydive-project/skydive,skydive-project/skydive,skydive-project/skydive,lebauce/skydive,skydive-project/skydive,lebauce/skydive,lebauce/skydive