adapts to pnnx

[xdream3]

This is a great study, I have never seen such an efficient algorithm, and I would appreciate it if you could develop code to adapt to pnnx

[guipotje]

Hi @PatrioticDedicated, thanks for your interest! Please check out the ONNX export provided by other contributors—I believe this could be helpful.

PR #5
https://github.com/meyiao/xfeatc