Support for YOLOv5 3.0/3.1

Added support for YOLOv5 3.0/3.1

external/yolov5-3.X/config_infer_primary.txt

@@ -0,0 +1,18 @@
+[property]
+gpu-id=0
+net-scale-factor=0.0039215697906911373
+model-color-format=0
+model-engine-file=yolov5s.engine
+labelfile-path=labels.txt
+num-detected-classes=80
+interval=0
+gie-unique-id=1
+process-mode=1
+network-type=0
+cluster-mode=4
+maintain-aspect-ratio=0
+parse-bbox-func-name=NvDsInferParseCustomYoloV5
+custom-lib-path=nvdsinfer_custom_impl_Yolo/libnvdsinfer_custom_impl_Yolo.so
+
+[class-attrs-all]
+pre-cluster-threshold=0.25