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

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

Document a lot of sparc64 internals.

Submitted by: marius
Reviewed by: ru
Approved by: re (blanket)
X-MFC: not before the code in RELENG_5 matches
these man pages or vice versa

Nits.

mdoc(7) police:
.Dt should have a third argument.
new sentence should start on its own line.
use precise width specifier.
Add AUTHORS section and correct device name to /dev/led/auxioled.

Approved by: jake (mentor)
Pointed by: ru

Port NetBSD auxio driver. The driver was modified to use led(4) and can
be used to announce various system activity.
The auxio device provides auxiliary I/O functions and is found on various
SBus/EBus UltraSPARC models. At present, only front panel LED is
controlled by this driver.

Approved by: jake (mentor)
Reviewed by: joerg
Tested by: joerg