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: 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)

Add a man page for the DNS accept filter.

Assorted markup, spelling, and grammar fixes.

Mdoc Janitor:

* Add a forgotten .An macro for 'Jeroen Ruigrok van der Werven'.

Noticed by: simon@

Mdoc Janitor:

* Add .Vt in the right places, transform some .Fa to .Vt, depending
on discussion context.

* When refering to the function malloc(), use .Fn, and not .Xr.

* Add `The' to prefix a sentence when describing a function, so
it results in ``The xxx() function..."

* Use `system call' instead of `syscall'.

* Improve the sentence which discusses accept_filt_generic_mod_event();
Talk about moduledata_t, and refer to the DECLARE_MODULE(9) manual
page.

* Properly markup .An (Author Name) throughout the AUTHORS section.

english(4) police.

de-__P()

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

mdoc(7) police: sort SEE ALSO xrefs (sort -b -f +2 -3 +1 -2).

Fixed missing include in synopsis.

Added evil #define of ACCEPT_FILTER_MODULE to synopsis. Some of
the functions defined in this man page aren't declared unless
ACCEPT_FILTER_MOD is defined before including <sys/socketvar.h>.

Xref accf_http and accf_data

Correct who pioneered the accept filters and Yahoo!'s company name.

Grammar police; "has been written by" --> "was written by".

attrib properly.

Pointed out by: asmodai

Document the kernel interface for accept filters.
Thanks to sheldonh for cleaning up the rough initial manpage.