- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
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

Update drm kernel drivers.

This is a sync to mesa/drm pre-gem, with a few fixes on top of that.
It also contains one local patch supplied by kib@ that I can't apply to
git.master shared code.

Approved by: flz
Obtained from: mesa/drm git.master
MFC after: 2 weeks