teach it to look for the following sequence in a destructor:
    delete m_pfoo;
    m_pfoo = nullptr;

Change-Id: Icd6271a63a024e32b53cc9e599f8f59952160380
Reviewed-on: https://gerrit.libreoffice.org/37900Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>