fix Class.getDeclaredMethods

getDeclaredMethods was returning methods which were inherited from a
superclass or superinterface but not (re)declared in the class itself,
due to the VM's internal use of VMClass.methodTable differing from its
role in reflection.  For reflection, we must use
ClassAddendum.methodTable if it's present (i.e. if it differs from
VMClass.methodTable).

This fixes https://github.com/ReadyTalk/avian/issues/185