Update clean targets

Update clean targets

* Remove chmod calls from make clean, arch is supposed to keep track
  of permissions correctly so they shouldn't be needed now.

* Add '-path './{arch}' -prune -o ' to all the find calls so cleaning
  doesn't recurse into arch's revision control directories and possibly
  corrupt them.

* Add archclean target which removes all of arch's cruft so release
  tarballs won't be ridiculously bloated (arch keeps a complete
  duplicate copy of the source making the tarball twice the size it
  should be, no good for release tarballs).  If people want a `archable'
  tree they should just use arch to check one out.
git-archimport-id: erbenson@alaska.net--public/yaboot--devel--1.3--patch-17