Merge ^/projects/release-arm-redux into ^/head.

Of note:

• This commit adds native FreeBSD/arm release build support without requiring out-of-tree utilities.

• Part of this merge removes the WANDBOARD-{SOLO,DUAL,QUAD} kernel configuration files, for which the IMX6 kernel configuration file should be used instead.

• The resulting images have a 'freebsd' user (password 'freebsd'), to allow ssh(1) access when console access is not available (VGA or serial). The default 'root' user password is set to 'root'.

• The /etc/ttys file for arm images now enable both ttyv0 and ttyu0 by default.

Help from: many (boot testing, feedback, etc.)
Sponsored by: The FreeBSD Foundation