WIP Radeon KMS branch

Hi,

I have ported the new radeonkms DRM driver and TTM memory manager from
FreeBSD to DragonFly.

TTM has already been pushed to the DragonFly repository and the radeonkms
driver is in this branch:
http://gitweb.dragonflybsd.org/~ftigeot/dragonfly.git/shortlog/refs/heads/drm_radeonkms

( Use this URL with git: git://leaf.dragonflybsd.org/~ftigeot/dragonfly.git 
and switch to the drm_radeonkms branch )

The radeonkms module can be loaded by itself without any apparent issue on my
hardware but the kernel crashes if a KMS-aware xf86-video-ati driver tries to
use it.

I won't have much time to try to debug this issue in the coming weeks/months,
it would be great if someone could have a look in the meantime.

A KMS-aware xorg driver can be built from git:
git://anongit.freedesktop.org/xorg/driver/xf86-video-ati

It will try to use the "radeon" module, so either rename
/boot/kernel/radeonkms.ko to /boot/kernel/radeon.ko
or change the drmOpen("radeon", busid) call to drmOpen("radeonkms", busid)
in src/radeon_kms.c

-- 
Francois Tigeot