Limit number of threads in CPU plugin of IE by OpenCV's getNumThreads

modules/dnn/src/op_inf_engine.cpp

@@ -460,6 +460,12 @@ void InfEngineBackendNet::initPlugin(InferenceEngine::ICNNNetwork& net)
                 CV_LOG_WARNING(NULL, "DNN-IE: Can't load extension plugin (extra layers for some networks). Specify path via OPENCV_DNN_IE_EXTRA_PLUGIN_PATH parameter");
             }
             // Some of networks can work without a library of extra layers.
+#ifndef _WIN32
+            // Limit the number of CPU threads.
+            enginePtr->SetConfig({{
+                InferenceEngine::PluginConfigParams::KEY_CPU_THREADS_NUM, format("%d", getNumThreads()),
+            }}, 0);
+#endif
         }
         plugin = InferenceEngine::InferencePlugin(enginePtr);