All it now does is function in a similar way to EXCLUDE_FROM_WORLD and
since we have a better named variable for this, lets just drop the
usage of BROKEN at the bitbake level.
(Bitbake rev: 8f4dcf794545273417d78ba18f51aa2b81606ae4)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>