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)

- Add missing xhci(4) manual page.
- Minor update in some USB manual pages.

MFC after: 3 days
Approved by: thompsa (mentor)

The NetBSD Foundation has granted permission to remove clause 3 and 4 from
their software.

Obtained from: NetBSD

Use the newly brought %U macro.

Make the SYNOPSIS section a bit more informative.

Update sound-related manpages to account for the recent change in
device and module naming. The following files were repo-copied:

csa.4 -> snd_csa.4
gusc.4 -> snd_gusc.4
maestro3.4 -> snd_maestro3.4
sbc.4 -> snd_sbc.4
uaudio.4 -> snd_uaudio.4

The pcm(4) manpage wasn't renamed to sound(4) as there are nearby
plans to rename "device sound" to "device snd", to address the
ambiguity in naming, so pcm.4 is linked to sound.4 for the moment.
(We also mumble something about the future plans in the manpage.)

Removed links from pcm.4 to als4000.4 and emu10k1.4 -- they now
have their own snd_*.4 manpages.

Fixes for recent snd_*.4 manpages: added missing "device sound"
to the SYNOPSIS, fixed hints (they are still "hint.pcm.<unit>"
in most cases).

MT5 after: 3 days

Remove dublicate words

MFC after: 3 days

Protect "e.g." from being interpreted as end of sentence.

Mechanically kill hard sentence breaks and double whitespaces.

Add a manual page for the USB Audio support in FreeBSD,
interfaced via the PCM framework.

This manual page was obtained from NetBSD, and the required
changes were made to adapt it to our uaudio driver.

Pre-cursor review: joe@