classes/packagegroup: add ability to disable complementary packages
This allows package group recipes that do not want the automatic
addition of complementary packages (e.g. for SDKs) to still inherit from
this class and thus it becomes very easy to determine if a recipe is a
package group which we need to do in certain circumstances.
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Saul Wold <sgw@linux.intel.com>
