Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Add support for SPARC64 V (and where it already makes sense for other
HAL/Fujitsu) CPUs. For the most part this consists of fleshing out the
MMU and cache handling, it doesn't add pmap optimizations possible with
these CPU, yet, though.
With these changes FreeBSD runs stable on Fujitsu Siemens PRIMEPOWER 250
and likely also other models based on SPARC64 V like 450, 650 and 850.
Thanks go to Michael Moll for providing access to a PRIMEPOWER 250.