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.

These IPv6-only tools have no explicit dependency on the INET6 macro.

Tested with: cmp(1)

Unbreak the build by dealing with an unexpected dependency on tcpdump source
present in ndp(8).

The vendor branch import uses a _U_ macro to apply the GCC 'unused' attribute
to the rcs ids embedded in each source file. Teach ndp about this.

Perform a major cleanup of the usr.sbin Makefiles.
These are not perfectly in agreement with each other style-wise, but they
are orders of orders of magnitude more consistent style-wise than before.

- Backout botched attempt to introduce MANSECT feature.
- MAN[1-9] -> MAN.

Set the default manual section for usr.sbin/ to 8.

libipsec and IPsec related apps. (and some KAME related man pages)

Reviewed by: freebsd-arch, cvs-committers
Obtained from: KAME project