...from SvtValueItemAcc to unrelated ValueItemAcc in ~SvtValueSetItem.  The
Svt* classes had been copied from the non-Svt* ones in
4883fd31 "weld ScTabBgColorDlg", but this
static_cast had apparently been missed when copying ~SvtValueSetItem from
~ValueSetItem (and the originally copied SvtValueItemAcc::ParentDestroyed had
later been removed with d4d03761
"loplugin:unusedmethods").  But the static_cast in ~ValueSetItem would never
have been necessary in the first place (though that needs partial reversal of
508c95f1 "improve passstuffbyref return
analysis", which had unhelpfully changed ValueSetItem::GetAccessible to return a
reference).

Change-Id: If1c9bb617ac4ad3c24371729504f9082594c048f
Reviewed-on: https://gerrit.libreoffice.org/72914
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>