Return the result we have already when getting an object with no name

This will ensure that something is set for the AutomationId based on
the actual object and the parents that do have object names until it
reaches one without an object name.

Pick-to: 6.1 6.0 5.15
Change-Id: I205485bc0ba772e321879e00e64ea8e1d8f1ba91
Reviewed-by: André de la Rocha <andre.rocha@qt.io>

src/plugins/platforms/windows/uiautomation/qwindowsuiamainprovider.cpp

@@ -513,7 +513,7 @@ QString QWindowsUiaMainProvider::automationIdForAccessible(const QAccessibleInte
         while (obj) {
             QString name = obj->objectName();
             if (name.isEmpty())
-                return QString();
+                return result;
             if (!result.isEmpty())
                 result.prepend(u'.');
             result.prepend(name);