The class adds an emtpy PACKAGES setting but most code now uses the
nopackages class which is much clearer. It also adds recursive do_build
dependencies which don't really serve any useful purpose any more.
Simplify the code and drop the class use.
(From OE-Core rev: 030d56e2e8ece93472adc51fe467221d846c9ac0)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>