Ninja Multi-Config: Fix cleaning of utility targets with commands

Source/cmNinjaUtilityTargetGenerator.cxx

@@ -100,6 +100,8 @@ void cmNinjaUtilityTargetGenerator::Generate(const std::string& config)
   if (genTarget->Target->GetType() != cmStateEnums::GLOBAL_TARGET) {
     lg->AppendTargetOutputs(genTarget, gg->GetByproductsForCleanTarget(),
                             config);
+    std::copy(util_outputs.begin(), util_outputs.end(),
+              std::back_inserter(gg->GetByproductsForCleanTarget()));
   }
   lg->AppendTargetDepends(genTarget, deps, config, config);