- 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

The argument corresponding to %zn is supposed to be an ssize_t *, not
a size_t *, although the distinction is moot in practice.

Correctly handle malloc() failure. While here, reduce the code size a
bit by removing some calls to the inline function addtype().

Reduce the level of duplication between vfprintf() and vfwprintf()
by moving the positional argument handling code to a new file,
printf-pos.c, and moving common definitions to printflocal.h.
No functional change intended.