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.
Ah, it was typing issues with the args char const *[] being passed into posix_spawn. Need to figure out how to fix this..