SceneGraph: don't do infinite recursion on deprecated Object::setClean().

Found thanks to (probably otherwise useless) GCC warning about usage of
deprecated function . Clang didn't emit such warning, because
even deprecated function should be able to call itself recursively.

src/Magnum/SceneGraph/Object.hpp

@@ -435,7 +435,7 @@ template<class Transformation> void Object<Transformation>::setClean(std::vector
         references.push_back(*o);
     }
 
-    return setClean(objects);
+    return setClean(references);
 }
 #endif