- 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

Use current SP instead of global data ptr for the U-Boot API signature search hint.

Global data (pointed by R2 on PowerPC) in principle is not guaranteed to be in
proximity of U-Boot heap (where the API signature is placed) accross different
architectures and platforms. Instead, use U-Boot stack pointer as a hint for
the search instead of the global data; this method tends to be more uniform
accross different platforms.

Obtained from: Semihalf

o Keep running on U-Boot's stack.
o Disable interrupts while not running U-Boot code. We clobber
registers that the U-Boot interrupt handlers assume to be
fixed as per the U-Boot register usage. At this time this only
applies to r14. U-Boot uses r2 now for what they used r29 for.
After we restore r14 in preparation of doing the syscall, we
re-enable interrupts. When we return from the syscall, we
disable interrupts and restore the callee-saved r14.

Move the $FreeBSD$ tag in a comment as __FBSDID doesn't work.

MFp4 (e500):

Add support for U-Boot. This uses the U-Boot API as developed by
Rafal and which is (will be) part of U-Boot 1.3.2 and later.

Credits to: raj@