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)

Correct subcommand name 'unset' -> 'unscript'.

Apply various fixes:

Silence mdoc(7) warnings;
Xref correct manual pages;
Point user to the ddb.8 manual page.

PR: 129398
Submitted by: gavin

DDB scripting, textdumps, output capture, etc, all will appear in
FreeBSD 7.1 before 8.0 ships.

Spotted by: Ulrich Spoerlein <uspoerlein at gmail dot com>
MFC after: 3 days

Add "ddb capture print" and "ddb capture status" commands do ddb(8),
alowing the DDB output capture buffer to be easily extracted from
user space. Both of these commands include -M/-N arguments, allowing
them to be used with kernel crash dumps (or /dev/mem).

This makes it easier to use DDB scripting and output capture with
minidumps or full dumps rather than with text dumps, allowing DDB
output (scripted or otherwise) to be easily extracted from a crash
dump.

MFC after: 1 week
Discussed with: brooks, jhb

- Normalize usage(), add "ddb pathname" syntax.
- Revise the manpage.

Add the ability to read a file of commands to ddb(8) modeled after the
feature in ipfw(8).

Minor formatting tweaks.

Point at ddb(4) and textdump(4) man pages for more script examples.

MFC after: 3 months

Add command-line tool ddb(8), which allows DDB(4) scripts to be
managed from userspace. It is largely a wrapper for sysctl()
calls, but because the sysctls for adding and removing scripts
are awkward to use directly, this provides an easier-to-use
interface.

MFC after: 3 months