use new logging flags

examples/cpp/network_routing_sat.cc

@@ -678,7 +678,7 @@ class NetworkRoutingSolver {
 }  // namespace operations_research
 
 int main(int argc, char** argv) {
-  absl::SetFlag(&FLAGS_logtostderr, true);
+  absl::SetFlag(&FLAGS_stderrthreshold, 0);
   InitGoogle(argv[0], &argc, &argv, true);
 
   operations_research::sat::NetworkRoutingData data;