Note vm.memguard.desc
Move stress2 to FreeBSD
Fix the ordering a bit so it only runs things once

Reap run_mmap_scripts.sh from the top-level directory (missed in previous commit)
Make memguard_uma_helper a bit more interesting

- Track all allocations and free them at the end
- Add the ability to keep the zone until the module's unloaded

Sponsored-by: EMC / Isilon Storage Division