Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Remove bridge(4) from the tree. if_bridge(4) is a full functional
replacement and has additional features which make it superior.

Discussed on: -arch
Reviewed by: thompsa
X-MFC-after: never (RELENG_6 as transition period)

vlan.h is obsolete, don't create it anymore.

Unbreak release. *sigh*

Add support for gigabit ethernet cards based on the NatSemi DP83820
and DP83821 gigabit ethernet MAC chips and the NatSemi DP83861 10/100/1000
copper PHY. There are a whole bunch of very low cost cards available with
this chipset selling for $150USD or less. This includes the SMC9462TX,
D-Link DGE-500T, Asante GigaNIX 1000TA and 1000TPC, and a couple cards
from Addtron.

This chip supports TCP/IP checksum offload, VLAN tagging/insertion.
2048-bit multicast filter, jumbograms and has 8K TX and 32K RX FIFOs.
I have not done serious performance testing with this driver. I know
it works, and I want it under CVS control so I can keep tabs on it.
Note that there's no serious mutex stuff in here yet either: I need
to talk more with jhb to figure out the right way to do this. That
said, I don't think there will be any problems.

This driver should also work on the alpha. It's not turned on in
GENERIC.