tx2使用pip安装onnx，解决Could not build wheels for onnx which use PEP 517 and cannot be installed directly

环境：tx2+cuda10.0+python3.6

        使用pip安装onnx失败，执行过程如下：

pip3 install onnx=="1.6.0"

报错：

ERROR: Failed building wheel for onnx
Failed to build onnx
ERROR: Could not build wheels for onnx which use PEP 517 and cannot be installed directly

        经过百度，查得：安装onnx需要protobuf编译所以安装前需要安装protobuf。

pip install numpy
pip install protobuf
sudo apt-get install protobuf-compiler libprotoc-dev
pip install onnx

        再次安装，成功。

pip3 install onnx=="1.6.0"

结果：