Merge the Isilon ATF code

This is a placeholder merge request to go over all of the items to ensure that I understand everything, some of the items from Isilon can be dropped as I dropped them from the atf branch (diff reduction), and make sure that any valid fixes from NetBSD can be pushed back.
Something else other than /etc/motd might be better. If only I could create files as a privileged user, drop privileges in the testcase and try and run it against that path.

I'd be worried about nuking critical paths though like /bin/sh, /usr/bin/make, etc. I think that's part of the reason why the test writers chose /usr/bin/fpr instead of something more common and potentially more critical.

/usr/bin/bc might be a better idea...