aufs-util: add new recipe

Introducing the aufs-util target recipe. This would be used in
conjuction with the aufs kernel feature to provide union mounts suitable
for live boot applications.

Only the target binaries are currently packages, with man pages,
libraries and other artifacts skipped in this initial integration.

(Integration work done by Bruce Ashfield <bruce.ashfield@windriver.com>
and Chen Qi <Qi.Chen@windriver.com> .)

Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>