- 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

Revive the LLVM and Clang license files, which were removed in my
too-thorough cleanup of unused files, in r213695. Also make sure these
get installed under /usr/share/doc.

Submitted by: rwatson, brooks
Pointy hat to: dim
MFC after: 3 days