Fix saving a quit.blend on exit when a file failed to load

When a file passed in from the command line failed to load,
blender would exit & save the quit.blend.

Resolve by adding a `do_user_exit_actions` to WM_exit_ex which is
false in backgrounds mode or when an error has occurred.

source/blender/python/intern/bpy_interface_atexit.c

@@ -22,7 +22,7 @@ static PyObject *bpy_atexit(PyObject *UNUSED(self), PyObject *UNUSED(args), PyOb
   /* close down enough of blender at least not to crash */
   struct bContext *C = BPY_context_get();
 
-  WM_exit_ex(C, false);
+  WM_exit_ex(C, false, false);
 
   Py_RETURN_NONE;
 }