Restoring toolbar visibility is broken on mac when unifiedTitleAndToolBarOnMac is set to true

To reproduce:

1) Apply the attached patch to demos/mainwindow.
2) Run it and uncheck Tool bars | Tool Bar 1 | Tool Bar 1
3) Close it and rerun - toolbars are correctly restored (Tool Bar 1 is hidden)
4) Uncomment line 102 in mainwindow.cpp : setUnifiedTitleAndToolBarOnMac(true);
5) Rerun the example - toolbars are not restored properly