Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Add support for booting PS3s from disk. This is still a little hackish until
we can find a way to get the information from petitboot or to guess it, so
the current algorithm is:

1. See if ps3disk3p1 (first GPT slice on OtherOS partition) exists, and if
so try to boot it.
2. Otherwise, netboot.

Submitted by: glevand <geoffrey.levand at mail dot ru >