eo: enforce auto_unref logic at the end of efl_unref execution.

This allow for the safe use of efl_ref/efl_unref around an efl_part
without calling any function on that part.

Reviewed-by: Marcel Hollerbach <mail@marcel-hollerbach.de>
Differential Revision: https://phab.enlightenment.org/D8358

src/lib/eo/eo.c

@@ -1993,6 +1993,9 @@ efl_unref(const Eo *obj_id)
           }
         _efl_unref(obj);
      }
+
+   _apply_auto_unref(obj, obj_id);
+
    _efl_unref(obj);
    EO_OBJ_DONE(obj_id);
 }