as observed by -fsanitize=vptr e.g. during CppunitTest_sc_filters_test (though
the true fix might be to prevent all this from happening during
~ScStyleSheetPool anyway?):

ScStyleSheet::GetItemSet()
ScStyleSheet::Notify(SfxBroadcaster&, SfxHint const&)
SfxBroadcaster::Broadcast(SfxHint const&)
SfxBroadcaster::~SfxBroadcaster()
SfxStyleSheet::~SfxStyleSheet()
ScStyleSheet::~ScStyleSheet()
cppu::OWeakObject::release()
comphelper::OWeakTypeObject::release()
rtl::Reference<SfxStyleSheetBase>::~Reference()
...
std::vector<rtl::Reference<SfxStyleSheetBase>, std::allocator<rtl::Reference<SfxStyleSheetBase>>>::clear()
svl::IndexedStyleSheets::Clear(svl::StyleSheetDisposer&)
SfxStyleSheetBasePool::Clear()
SfxStyleSheetBasePool::~SfxStyleSheetBasePool()
SfxStyleSheetPool::~SfxStyleSheetPool()
ScStyleSheetPool::~ScStyleSheetPool()
cppu::OWeakObject::release()
comphelper::OWeakTypeObject::release()
rtl::Reference<ScStyleSheetPool>::clear()
ScPoolHelper::~ScPoolHelper()
salhelper::SimpleReferenceObject::release()
rtl::Reference<ScPoolHelper>::clear()
ScDocument::~ScDocument()
ScDocShell::~ScDocShell()
...

Change-Id: I1565f8dbd039de20f63ac20d6b86d7b0d2799637