- 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

Allow psaddr_t to be widened by using thr_pread_{int,long,ptr},
where critical. Some places still use ps_pread/ps_pwrite directly,
but only need changed when byte-order comes into the picture.
Also, change th_p in td_event_msg_t from a pointer type to
psaddr_t, so that events also work when psaddr_t is widened.

Replace internal usage of struct umtx with umutex which can supports
real-time if we want, no functionality is changed.

Add missing event reporting code.