Fix lifetime of networks which are loaded from Model Optimizer IRs

modules/dnn/src/op_inf_engine.cpp

@@ -161,6 +161,7 @@ InfEngineBackendNet::InfEngineBackendNet(InferenceEngine::CNNNetwork& net)
     inputs = net.getInputsInfo();
     outputs = net.getOutputsInfo();
     layers.resize(net.layerCount());  // A hack to execute InfEngineBackendNet::layerCount correctly.
+    netOwner = net;
 }
 
 void InfEngineBackendNet::Release() noexcept

modules/dnn/src/op_inf_engine.hpp

@@ -131,6 +131,8 @@ private:
     InferenceEngine::InferencePlugin plugin;
     InferenceEngine::ExecutableNetwork netExec;
     InferenceEngine::InferRequest infRequest;
+    // In case of models from Model Optimizer we need to manage their lifetime.
+    InferenceEngine::CNNNetwork netOwner;
 
     std::string name;