kernel-ng-util: add explicit setuptools dependency

Signed-off-by: Gregory M. Tuner <gmt@be-evil.net>
add dev-python/wrapt (dependency)

Signed-off-by: Gregory M. Tuner <gmt@be-evil.net>
add some crufty notes on selecting files

Signed-off-by: Gregory M. Tuner <gmt@be-evil.net>