Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r246134 ...

Improve devd startup time, by tweaking some string handling routines that are
heavily used when parsing config files. Mostly these changes avoid making
temporary copies of the strings, and avoid doing byte at a time append
operations, on the most-used code path.

On a 1.2 GHz ARM processor this reduces the time to parse the config files
from 13 to 6 seconds.

MFC r226775:

- Add support for a "!" character in regex matching in devd(8). It inverts
the logic (true/false) of the matching.

- Add "!usbus[0-9]+" to IFNET ATTACH notification handler in the default
devd.conf to prevent rc.d/netif from running when usbus[0-9]+ is attached.

MFC r243930:
Constify where possible

Approved by: cperciva (mentor, implicit)

MFC r243932:
Prefer the use of initalizer lists to ctor assignment.

Approved by: cperciva (implicit)

MFC r228618

In sbin/devd/devd.h, 'event_proc' and 'eps' are declared as structs. In
devd.hh, they are redeclared as classes. Fix the inconsistency.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Expand system into my_system, and add the necessary tidyness that we
need. Close the pidfile. Then close all descriptors >= 3 to avoid
information leakage to children.

This solves the problem of not being able to restart devd when you
have, for example, a dhclient forked to configure your network...

MFC after: 3 days

Minor initialization change to not trigger bogus gcc warning about
passing literal strings to the constructors of string.

Use pidfile(3).

OK'ed by: imp

Add the ability to match the on a media type of the device in question.

Submitted by: sam
Approved by: re (scottl)

Parse the ! lines that will soon be coming from the kernel. These are
a generalized notification mechanism for subsystems wishing to report
events.

Revieded by: njl

# The kernel side seems like it might be causing panics for me, but should
# be forthcoming shortly.

Create a new C++ header file called devd.hh which has all the class
definitions in it. Begin to document the classes that we use, and how
they interrelate (using comments that I can use with doxygen to
automatically generate docs with).