make clean will remove more than just artifacts

[MarcKarasek]

I used your code as a template for non-blocking socket for verilog.

Not looking at the make clean, I created a server.c file to replace the .py one.
Also created a local git repo and checked all my code in so I could manage changes.

When I did a make clean, it removed the server.c file, cleaned out he .git dir.

[MarcKarasek]

You should not use find. in a clean target as you can never guarantee that it will not find other things..