The class is mainly an image based class but one recipe does need to look
at values shared with the class and isn't an image. Move this to a conf
file instead, avoiding the need to pollute all recipes globally.
(From OE-Core rev: ed4238487c81b3580e83c257b50745a832a6e717)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
