Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC r233628, r234598, r235229, r235831, r226986.

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: r231871

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)

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

mdoc cleanup

Garbage collect unused sections, macros and arguments. Fix prologue and
remove empty lines.

Found by: mdocml

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)

- Support for uncore counting events: one fixed PMC with the uncore
domain clock, 8 programmable PMC.
- Westmere based CPU (Xeon 5600, Corei7 980X) support.
- New man pages with events list for core and uncore.
- Updated Corei7 events with Intel 253669-033US December 2009 doc.
There is some removed events in the documentation, they have been
kept in the code but documented in the man page as obsolete.
- Offcore response events can be setup with rsp token.

Sponsored by: NETASQ