classes/lib: Update to explictly create lists where needed

Iterators now return views, not lists in python3. Where we need
lists, handle this explicitly.

(From OE-Core rev: caebd862bac7eed725e0f0321bf50793671b5312)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oe/classutils.py

@@ -34,7 +34,7 @@ abstract base classes out of the registry)."""
 
     @classmethod
     def prioritized(tcls):
-        return sorted(tcls.registry.values(),
+        return sorted(list(tcls.registry.values()),
                       key=lambda v: v.priority, reverse=True)
 
     def unregister(cls):