[App] get rid of MSCV compiler warning
[App] get rid of MSCV compiler warning

the same as in https://github.com/FreeCAD/FreeCAD/pull/4053

Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master