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

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

mdoc(7) police: markup fixes.

Approved by: re

Some BIOSs are using MTRR values that are only documented under NDA
to control the mapping of things like the ACPI and APM into memory.

The problem is that starting X changes these values, so if something
was using the bits of BIOS mapped into memory (say ACPI or APM),
then next time they access this memory the machine would hang.

This patch refuse to change MTRR values it doesn't understand,
unless a new "force" option is given. This means X doesn't change
them by accident but someone can override that if they really want
to.

PR: 28418
Tested by: Christopher Masto <chris@netmonger.net>,
David Bushong <david@bushong.net>,
Santos <casd@myrealbox.com>
MFC after: 1 week

The .Nm utility

Remove whitespace at EOL.

mdoc(7) police: removed HISTORY info from the .Os call.

mdoc(7) police: normalize .Nd.

mdoc(7) police: use the new features of the Nm macro.

Remove single-space hard sentence breaks. These degrade the quality
of the typeset output, tend to make diffs harder to read and provide
bad examples for new-comers to mdoc.

Remove an unnecessary cross-reference to ioctl(2)

Add and activate the man page for memcontrol(8).

Reviewed by: msmith