null out black canvas handle when freed - just in case.
null out black canvas handle when freed - just in case.



SVN revision: 69593

FlorentRevest/Enlightenment,tizenorg/platform.upstream.enlightenment,FlorentRevest/Enlightenment,tizenorg/platform.upstream.enlightenment,rvandegrift/e,tasn/enlightenment,FlorentRevest/Enlightenment,tasn/enlightenment,rvandegrift/e,tizenorg/platform.upstream.enlightenment,tasn/enlightenment,rvandegrift/e