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

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

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

Approved by: re (implicit)

mdoc: Garbage collect unused/unneeded macros

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)

Attempt to clarify some confusing wording regarding atomic_load() and
atomic_store().

Implement atomic_fetchadd_long() for all architectures and document it.

Reviewed by: attilio, jhb, jeff, kris (as a part of the uidinfo_waitfree.patch)

-mdoc sweep.

- Document atomic_fetchadd(9) and add a MLINK.
- Add arm and ppc to the list of archs not supporting operations on 64-bit
integers.
- Update the sample code for acquiring a mutex to be more recent and to
take into account the recent atomic_foo_ptr() changes.

MFC after: 1 week

Some mdoc(7) fixes:

Nuke incorrect usage of .Ar; replace it with .Vt, .Va or .Fa appropriately.
The .Ar mdoc(7) specifier should only be used when displaying command line
arguments.

Approved by: des (mentor)

mdoc(7) police: removed raw troff from previous delta.

Objected to by: mpp, jhb

mdoc(7) police:

- make SYNOPSIS look better with some troff magic
- tidy up the markup

ispell sweep of share/man/man9/*.

Note that the atomic ops on char and short data types may not be available
on all architectures. Sparc64 does not implement them.

mdoc(7) police: Use the new .In macro for #include statements.

Fixed double word typo.
MFC after: 7 days

Add 2001 to copyright.

Fixed missing and/or wrong and/or extra includes in synopsis.

Fix some nits in the globs used to describe the various sets of atomic
operations.

Submitted by: jake, jasone

Add a manpage to document the atomic operations including a quick treatment
of memory barriers and the newish atomic variants that include them.

Reviewed by: sheldonh