...(by inlining all its virtual functions), as otherwise -fsanitize=undefined
makes sc require ScValidationDlg RTTI (to verify the cast to ScValidationDlg in
the ScValidityRefChildWin ctor in sc/source/ui/view/reffact.cxx) but which would
only be emitted in scui (against which sc cannot link).

Change-Id: Id9e2bf0719ba3bba35e5ae1f0e58190d9fdb6dd4