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)

The last big commit: let usr.sbin/ use WARNS=6 by default.

Update bmake glue for the BIND 9.4.1 import.

This includes a return to building with threads, since one of the
major focuses of the 9.4.x branch is to improve thread performance.

Disable thread support in BIND. It appears to reduce performance rather
than increase it, and seems to be the cause of the memory leaks which some
users have reported.

Requested by: dougb
MFC after: 5 days

Don't expose BIND libraries and their headers to the public by default,
but have a knob (WANT_BIND_LIBS) to build and install them in /usr/lib
and /usr/include. Rumors are that this may be useful at a later point,
let's see.

What this really means is that all BIND libraries are now internal to
buildworld (by default, unless WANT_BIND_LIBS is defined), and linked
statically into various BIND executables.

While here, removed redundant -I's from CFLAGS in lib/bind makefiles.

Sponsored by: des
OK'ed by: dougb

Clean up and comment config.mk. Centralize more stuff. Bitch if
POSIX threads libraries are not available. Add crypto support if
the crypto libraries are available. Build dnssec-{keygen,signzone}
if crypto is available.

Submitted by: (in part) dougb@

Switch from BIND 8 to BIND 9.

Submitted by: (in part) dougb@, trhodes@
Reviewed by: dougb@, trhodes@, re@
MFC after: 5 days