compat-drivers: improve git-paranoia with git clean

compat-drivers: improve git-paranoia with git clean

git clean can be used to further sanitize releases.

git clean -x -d -f

Will spit shine your release from any even files
you may have lying around that you tell git to
ignore. We use the -n option to git clean to warn
the user of unwanted content. If someone is really
make releases they should read and understand
git clean man pages and also understand that
running git-paranoia with -c will wipe out clean
all content found by 'git clean -x -d -n'.

Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>