qdoc: Pages with multiple \ingroup commands lose navigation to parent \group

QDoc adds a link to the parent \group in the navigation links (breadcrumbs) for a page that uses the \ingroup command. However, this step is omitted if there are multiple \ingroup commands in use - even if the extra \ingroup commands are used only for grouping with \generatelist, and do not reference an existing \group page.

As there might still be only a single valid link target (a named \group page with a \title), this logic should be revised to handle that.