- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

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

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

drm/radeon: Import the Radeon KMS driver

This driver is based on Linux 3.8 and a previous effort by kan@.

More informations about this project can be found on the FreeBSD wiki:
https://wiki.freebsd.org/AMD_GPU

The driver is split into:

sys/dev/drm2:
The driver sources.

sys/modules/drm2/radeonkmw:
The driver main kernel module's Makefile.

sys/modules/drm2/radeonkmsfw:
All firmware kernel module Makefiles. There's one directory and one
Makefile for each firmware.

sys/contrib/dev/drm2/radeonkmsfw:
All firmware binary sources.

tools/tools/drm/radeon
Tools to update firmwares or regenerate some headers.

Merging the driver to FreeBSD 9.x may be possible but not a priority for
now.

Help from: kib@, kan@
Tested by: avg@, kwm@, ray@,
Alexander Yerenkow <yerenkow@gmail.com>,
Anders Bolt-Evensen <andersbo87@me.com>,
Denis Djubajlo <stdedjub@googlemail.com>,
J.R. Oldroyd <fbsd@opal.com>,
Mikaël Urankar <mikael.urankar@gmail.com>,
Pierre-Emmanuel Pédron <pepcitron@gmail.com>,
Sam Fourman Jr. <sfourman@gmail.com>,
Wade <wade-is-great@live.com>,
(probably other I forgot...)
HW donations: kyzh, Yakaz