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

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

In man section 4, ERRORS is spelled DIAGNOSTICS

mdoc: move CAVEATS, BUGS and SECURITY CONSIDERATIONS sections to the
bottom of the manpages and order them consistently.

GNU groff doesn't care about the ordering, and doesn't even mention
CAVEATS and SECURITY CONSIDERATIONS as common sections and where to put
them.

Found by: mdocml lint run
Reviewed by: ru

Move two periods out of quotes and to where they belong.

MFC after: 1 day

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