RFE: PC installations should mandate dump and swap devices

[wesolows]

We keep letting operators get to a seemingly functional multiuser installation of illumos that lacks either a dump device or a swap device or both. These configurations either don't work (no swap => fork failures, ENOSPC in /tmp, ...) or can't be debugged when something goes wrong. Both adequate swap space and a reasonably sized dump device should be mandatory to "complete installation" on PCs. There will be temptation to allow some kind of I know what I'm doing override; resist it. These storage areas are mandatory and anyone who asserts he or she knows better is proving that assertion false by making it.