- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

Commit initial (unfinished!) support for the AR933x series of embedded
CPUs.

The AR933x is a mips24k based SoC with an AR9380 series SoC on board,
two gigabit ethernet interfaces and an internal 10/100mbit ethernet
switch. There's also the normal interfaces (USB, ethernet, uart, GPIO.)

The downside? There's a non-ns8250 UART device.

With a very basic UART driver (not in this commit) the SoC is initialised
and boots up. I'll commit the UART code soon and then link it into the
general setup path.

This code is a re-implementation based from the Linux kernel / openwrt
AR933x support.

TODO:

* UART (obviously)
* All of the ethernet, USB and wifi SoC glue, including ethernet PLL
programming.