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 r235782:
A rewrite of the i810 bits of the agp(4) driver. New driver supports
operations required by GEMified i915.ko. It also attaches to SandyBridge
and IvyBridge CPU northbridges now.

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

Approved by: re (implicit)

Move the agp(4) driver from sys/pci to sys/dev/agp. __FreeBSD_version was
bumped to 800004 to note the change though userland apps should not be
affected since they use <sys/agpio.h> rather than the headers in
sys/dev/agp.

Discussed with: anholt
Repocopy by: simon

Don't map the AGP aperture into contiguous KVA. The various graphics
drivers already map sections into KVA as needed anyway. Note that this
will probably break the nvidia driver, but I will coordinate to get that
fixed.

MFC after: 2 weeks

Allow retrieval of the virtual address of the AGP aperture
using agp_get_info().

MFC after: 1 week

A driver for programming the AGP hardware. This is only very lightly
tested on Intel BX chipsets only. The other agp minidrivers are totally
untested.

The programming api is a subset of the Linux api and is only intended to
be enough for the X server to use. There is also an in-kernel api for the
use of other kernel modules such as the 3D DRI.