make clean: also clean up generated version files
make clean: also clean up generated version files

We also discussed using "git clean -dXf" but that could remove files
that were not generated by make.

Closes #4619

mawww/kakoune,jkonecny12/kakoune,jkonecny12/kakoune,mawww/kakoune,mawww/kakoune,mawww/kakoune,jkonecny12/kakoune,jkonecny12/kakoune