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)

o Fix prototype for SYSCALL_MODULE(9): the third argument
is a pointer to struct sysent. Correct its description.

PR: docs/84790
Submitted by: Dirk Gouders
MFC after: 2 weeks

Use a .Bl -tag list instead of plain .Pp paragraphs for describing the
macro arguments expected by SYSCALL_MODULE().

MFC after: 3 days

mdoc(7): Use the new feature of the .In macro.

Update function definitions and required include files to reflect
the current state of the system.

Approved by: alfred

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

Improve description of "new_sysent".

Add SYSCALL_MODULE.9, a manpage for the SYSCALL_MODULE wrapper macro
for syscall klds.

Some text of this manpage is based on the comments in the example
syscall module written by Assar Westerlund.

Reviewed by: ru