...which showed that checking the parent statement (which may be too large to)
in OnceVar::VisitDeclRefExpr is inadequate.

Change-Id: I07fb8ba9e2dfbd0c65a2723737d14abcddcefec4
Reviewed-on: https://gerrit.libreoffice.org/39757Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Stephan Bergmann <sbergman@redhat.com>