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)

Mechanically kill hard sentence breaks and double whitespaces.

mdoc(7) police: tidy up previous delta.

o sysctl.conf cannot be used to set sysctls that are present in
unloaded kernel modules. Remove the example linux compat sysctls
because they break if the linux emulator is loaded as a module, rather
than compiled in. Add a BUGS entry indicating as much.

Reported by: jack <jack@germanium.xtalwind.net>
MFC after: 3 days

mdoc(7) police: join OS version with the corresponding macro.

mdoc(7) police: protect trailing full stops of abbreviations
with a trailing zero-width space: `e.g.\&'.

Since the ``-w'' sysctl(8) option has been deprecated,
don't mention it in the manpages.

Removed whitespace at end-of-line; no content changes. I simply did
cd src/share; find man[1-9] -type f|xargs perl -pi -e 's/[ \t]+$//'

BTW, what editors are the culprits? I'm using vim and it shows
me whitespace at EOL in troff files with a thick blue block...

Reviewed by: Silence from cvs diff -b
MFC after: 7 days

mdoc(7) police: removed punctuation after the last SEE ALSO xref.

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

mdoc(7) police: normalize .Nd.

Prepare for mdoc(7)NG.

Use Fx macro wherever possible.

Add HISTORY.

Add and document support for handling comments and blank lines
in /etc/sysctl.conf.

Reviewed by: imp, jkh

Replace a conjunction "you're" with "you are". This makes
reading by non-native English speakers a little bit easier, and
follows some basic doc guidelines.

Add and active the manual page for /etc/sysctl.conf.