- 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

Merge in support for Xen HVM on amd64 architecture.

Pull in support for Xen HVM from user/dfr/xenhvm/6.

Major cleaning up and refactoring, including but not limited to:

* Move MI Xen headers from <machine/xen/foo.h> to <xen/foo.h>
* Try to cut down the amount of times one include cross-includes another
* Remove all the linux compatibiity macros in favour of an unobfuscated
native FreeBSD style.
* Don't multiplex error and result values using negative errno return values.
* On FreeBSD, malloc(..., M_WAITOK) doesn't return NULL - simplify accordingly.

Add some Xen support for amd64 - initially HVM only.

Clone Kip's Xen on stable/6 tree so that I can work on improving FreeBSD/amd64
performance in Xen's HVM mode.

- pull in xen_machdep.c from HEAD
- pull in xen changes to common files
- remove unused i386/xen/machdep.c

Add i386 specific xen support