cogl-object: correctly free user_data_array in _unref

If there is private data associated with a CoglObject then there may be
a user_data_array that needs to be freed. The code was mistakenly
freeing the array inside the loop that was actually iterating over the
user data array notifying the objects destruction instead of waiting
until all the data entries had been destroyed.

cogl/cogl-object.c

@@ -86,9 +86,8 @@ cogl_object_unref (void *object)
                   if (entry->destroy)
                     entry->destroy (entry->user_data);
                 }
+              g_array_free (obj->user_data_array, TRUE);
             }
-
-          g_array_free (obj->user_data_array, TRUE);
         }
 
       COGL_OBJECT_DEBUG_FREE (obj);