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)

Merge Cavium Octeon SDK 2.0 Simple Executive; this brings some fixes and new
facilities as well as support for the Octeon 2 family of SoCs.

XXX Note that with our antediluvian assembler, we can't support some Octeon 2
instructions and fall back to using the old ones instead.

Import Cavium Octeon SDK 2.0 Simple Executive from cnusers.org.