convert_tool module can not be compiled correctly by vs2017

[TingfengTang]

I use CMake-3.14.5-gui to generate the project which contains the convert_tool module only, then compile the project and get the following error:

2>Done building project "tengine-lite-static.vcxproj".
3>------ Build started: Project: convert_tool (tools\convert_tool\convert_tool), Configuration: Debug x64 ------
3>Generating onnx/onnx.pb.cc
3>命令语法不正确。
3>D:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\Common7\IDE\VC\VCTargets\Microsoft.CppCommon.targets(171,5): error MSB6006: "cmd.exe" exited with code 1.

I have checked the Protobuf configure and compile the test module, but this subproject works well.