tdf#101821 sw: fix layout footnote use-after-free in SwRootFrame

tdf#101821 sw: fix layout footnote use-after-free in SwRootFrame

The ClearSwLayouterEntries() accesses anchored objects and if they are
anchored in footnotes then RemoveFootnotes() has already deleted them.

(regression from 962d0500c4debaef43e5f146e47e08c66d851562)

Invalid write of size 1
   at 0x4143CCB3: SwAnchoredObject::SetTmpConsiderWrapInfluence(bool) (anchoredobject.cxx:739)
   by 0x414D8A21: SwObjsMarkedAsTmpConsiderWrapInfluence::Clear() (objstmpconsiderwrapinfl.cxx:58)
   by 0x414C943E: SwLayouter::ClearObjsTmpConsiderWrapInfluence(SwDoc const&) (layouter.cxx:401)
   by 0x411DBE57: sw::DocumentLayoutManager::ClearSwLayouterEntries() (DocumentLayoutManager.cxx:504)
   by 0x414D05D9: SwRootFrame::DestroyImpl() (newfrm.cxx:594)
   by 0x41535AB3: SwFrame::DestroyFrame(SwFrame*) (ssfrm.cxx:389)
   by 0x419E8171: std::_Sp_counted_deleter<SwRootFrame*, void (*)(SwFrame*), std::allocator<void>, (__gnu_cxx::_Lock_policy)2>::_M_dispose() (shared_ptr_base.h:464)
   by 0x40EB6DB5: std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release() (shared_ptr_base.h:150)
   by 0x40EB5E76: std::__shared_count<(__gnu_cxx::_Lock_policy)2>::~__shared_count() (shared_ptr_base.h:662)
   by 0x419E65F9: std::__shared_ptr<SwRootFrame, (__gnu_cxx::_Lock_policy)2>::~__shared_ptr() (shared_ptr_base.h:928)
   by 0x419E6615: std::shared_ptr<SwRootFrame>::~shared_ptr() (shared_ptr.h:93)
   by 0x419E619D: SwViewShell::~SwViewShell() (vnew.cxx:285)
  Address 0x5feb6eee is 334 bytes inside a block of size 488 free'd
   at 0x4C2F21A: operator delete(void*) (vg_replace_malloc.c:576)
   by 0x41488962: SwFlyAtContentFrame::~SwFlyAtContentFrame() (flyfrms.hxx:134)
   by 0x41535AFC: SwFrame::DestroyFrame(SwFrame*) (ssfrm.cxx:391)
   by 0x415360BD: SwLayoutFrame::DestroyImpl() (ssfrm.cxx:477)
   by 0x41535AB3: SwFrame::DestroyFrame(SwFrame*) (ssfrm.cxx:389)
   by 0x414A2FF4: sw_RemoveFootnotes(SwFootnoteBossFrame*, bool, bool) (ftnfrm.cxx:852)
   by 0x414A3104: sw_RemoveFootnotes(SwFootnoteBossFrame*, bool, bool) (ftnfrm.cxx:874)
   by 0x414A321A: SwRootFrame::RemoveFootnotes(SwPageFrame*, bool, bool) (ftnfrm.cxx:897)
   by 0x414D0558: SwRootFrame::DestroyImpl() (newfrm.cxx:585)
   by 0x41535AB3: SwFrame::DestroyFrame(SwFrame*) (ssfrm.cxx:389)
   by 0x419E8171: std::_Sp_counted_deleter<SwRootFrame*, void (*)(SwFrame*), std::allocator<void>, (__gnu_cxx::_Lock_policy)2>::_M_dispose() (shared_ptr_base.h:464)
   by 0x40EB6DB5: std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release() (shared_ptr_base.h:150)
   by 0x40EB5E76: std::__shared_count<(__gnu_cxx::_Lock_policy)2>::~__shared_count() (shared_ptr_base.h:662)
   by 0x419E65F9: std::__shared_ptr<SwRootFrame, (__gnu_cxx::_Lock_policy)2>::~__shared_ptr() (shared_ptr_base.h:928)
   by 0x419E6615: std::shared_ptr<SwRootFrame>::~shared_ptr() (shared_ptr.h:93)
   by 0x419E619D: SwViewShell::~SwViewShell() (vnew.cxx:285)

Change-Id: I147f46d49c90de46189ad34feed66c289adddc15

Gbp-Pq: Name layout-footnote-use-after-free.diff