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

MFC r263446

Update hwpmc to support core events for Atom Silvermont microarchitecture.
(Model 0x4D as per Intel document 330061-001 01/2014)

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

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

Add software PMC support.

New kernel events can be added at various location for sampling or counting.
This will for example allow easy system profiling whatever the processor is
with known tools like pmcstat(8).

Simultaneous usage of software PMC and hardware PMC is possible, for example
looking at the lock acquire failure, page fault while sampling on
instructions.

Sponsored by: NETASQ
MFC after: 1 month

Switch the license boilerplates to our standard one.

Advantages:
- Reduces the number of different license versions in the tree
- Eliminates a typo
- Removes some incorrect author attributions due to c/p
- Removes c/p error potential for future pmc manpages

Approved by: jkoshy, gnn, rpaulo, fabient (copyright holders)
MFC after: 1 week

mdoc: order prologue macros consistently by Dd/Dt/Os

Although groff_mdoc(7) gives another impression, this is the ordering
most widely used and also required by mdocml/mandoc.

Reviewed by: ru
Approved by: philip, ed (mentors)

Use US spellings, fix typos.

Fix typos.

Reported by: Harald Servat <redcrash at gmail dot com>

Update description of an event.

Submitted by: "Verplanke, Edwin" <edwin dot verplanke at intel dot com>

Correction: these PMCs do not support a "umask" modifier.

Tweak -mdoc usage.

Remove duplicates, fix errors and document UMASK values.

Document the alternate event names supported for "architectural" PMC events.

Add manual pages for performance measurement counters present in
Intel Atom(tm), Core(tm) and Core2(tm) CPUs.