After inserting a header in the bugdoc, during SwFrame::Calc of a
SwTextFrame that is in a footnote, it decides move forward to the next
page.  This deletes the SwFootnoteFrame and SwFootnoteContFrame that
lcl_FormatContentOfLayoutFrame() are iterating over.

For want of a more elegant solution, use a big hammer to prevent the
problem and try to clean up so that no empty SwFootnoteFrame and
SwFootnoteContFrame remain (as that is known to crash in other places,
see commit c9fb3476)

Invalid read of size 8
   at 0x414E1F96: SwFrame::GetNext() (frame.hxx:485)
   by 0x41AFDD07: lcl_FormatContentOfLayoutFrame(SwLayoutFrame*, SwFrame*) (objectformattertxtfrm.cxx:646)
   by 0x41AFDCC0: lcl_FormatContentOfLayoutFrame(SwLayoutFrame*, SwFrame*) (objectformattertxtfrm.cxx:642)
   by 0x41AFDCC0: lcl_FormatContentOfLayoutFrame(SwLayoutFrame*, SwFrame*) (objectformattertxtfrm.cxx:642)
   by 0x41AFDEA7: SwObjectFormatterTextFrame::FormatAnchorFrameAndItsPrevs(SwTextFrame&) (objectformattertxtfrm.cxx:696)
   by 0x41AAA680: SwFlyAtContentFrame::MakeAll(OutputDevice*) (flycnt.cxx:415)
   by 0x41A7F211: SwFrame::PrepareMake(OutputDevice*) (calcmove.cxx:346)
   by 0x41B75758: SwFrame::Calc(OutputDevice*) const (trvlfrm.cxx:1761)
   by 0x41AA8927: SwFlyFrame::Calc(OutputDevice*) const (fly.cxx:2559)
   by 0x41ADB36B: SwLayAction::FormatLayoutFly(SwFlyFrame*) (layact.cxx:1414)
   by 0x41AF9658: SwObjectFormatter::FormatObj_(SwAnchoredObject&) (objectformatter.cxx:321)
   by 0x41AFCB6E: SwObjectFormatterTextFrame::DoFormatObj(SwAnchoredObject&, bool) (objectformattertxtfrm.cxx:126)
   by 0x41AF9A6A: SwObjectFormatter::FormatObjsAtFrame_(SwTextFrame*) (objectformatter.cxx:443)
   by 0x41AFD275: SwObjectFormatterTextFrame::DoFormatObjs() (objectformattertxtfrm.cxx:328)
   by 0x41AF924A: SwObjectFormatter::FormatObjsAtFrame(SwFrame&, SwPageFrame const&, SwLayAction*) (objectformatter.cxx:191)
   by 0x41ADC213: SwLayAction::FormatContent(SwPageFrame const*) (layact.cxx:1633)
   by 0x41AD88DE: SwLayAction::InternalAction(OutputDevice*) (layact.cxx:760)
   by 0x41AD7080: SwLayAction::Action(OutputDevice*) (layact.cxx:351)
   by 0x41ADE32E: SwLayIdle::SwLayIdle(SwRootFrame*, SwViewShellImp*) (layact.cxx:2133)
   by 0x41FFC97E: SwViewShell::LayoutIdle() (viewsh.cxx:711)
 Address 0x505541a8 is 72 bytes inside a block of size 272 free'd
   at 0x4C2F21A: operator delete(void*) (vg_replace_malloc.c:576)
   by 0x41AD371A: SwFootnoteFrame::~SwFootnoteFrame() (ftnfrm.hxx:52)
   by 0x41B5B74C: SwFrame::DestroyFrame(SwFrame*) (ssfrm.cxx:391)
   by 0x41A97294: SwFlowFrame::CutTree(SwFrame*) (flowfrm.cxx:406)
   by 0x41A979AE: SwFlowFrame::MoveSubTree(SwLayoutFrame*, SwFrame*) (flowfrm.cxx:592)
   by 0x41ACFB69: SwContentFrame::MoveFootnoteCntFwd(bool, SwFootnoteBossFrame*) (ftnfrm.cxx:2756)
   by 0x41A9B78E: SwFlowFrame::MoveFwd(bool, bool, bool) (flowfrm.cxx:1813)
   by 0x41A85864: SwContentFrame::MakeAll(OutputDevice*) (calcmove.cxx:1681)
   by 0x41A7F211: SwFrame::PrepareMake(OutputDevice*) (calcmove.cxx:346)
   by 0x41B75758: SwFrame::Calc(OutputDevice*) const (trvlfrm.cxx:1761)
   by 0x41AFDCFB: lcl_FormatContentOfLayoutFrame(SwLayoutFrame*, SwFrame*) (objectformattertxtfrm.cxx:644)
   by 0x41AFDCC0: lcl_FormatContentOfLayoutFrame(SwLayoutFrame*, SwFrame*) (objectformattertxtfrm.cxx:642)
   by 0x41AFDCC0: lcl_FormatContentOfLayoutFrame(SwLayoutFrame*, SwFrame*) (objectformattertxtfrm.cxx:642)
   by 0x41AFDCC0: lcl_FormatContentOfLayoutFrame(SwLayoutFrame*, SwFrame*) (objectformattertxtfrm.cxx:642)
   by 0x41AFDEA7: SwObjectFormatterTextFrame::FormatAnchorFrameAndItsPrevs(SwTextFrame&) (objectformattertxtfrm.cxx:696)
   by 0x41AAA680: SwFlyAtContentFrame::MakeAll(OutputDevice*) (flycnt.cxx:415)
   by 0x41A7F211: SwFrame::PrepareMake(OutputDevice*) (calcmove.cxx:346)
   by 0x41B75758: SwFrame::Calc(OutputDevice*) const (trvlfrm.cxx:1761)
   by 0x41AA8927: SwFlyFrame::Calc(OutputDevice*) const (fly.cxx:2559)
   by 0x41ADB36B: SwLayAction::FormatLayoutFly(SwFlyFrame*) (layact.cxx:1414)
   by 0x41AF9658: SwObjectFormatter::FormatObj_(SwAnchoredObject&) (objectformatter.cxx:321)
   by 0x41AFCB6E: SwObjectFormatterTextFrame::DoFormatObj(SwAnchoredObject&, bool) (objectformattertxtfrm.cxx:126)
   by 0x41AF9A6A: SwObjectFormatter::FormatObjsAtFrame_(SwTextFrame*) (objectformatter.cxx:443)
   by 0x41AFD275: SwObjectFormatterTextFrame::DoFormatObjs() (objectformattertxtfrm.cxx:328)
   by 0x41AF924A: SwObjectFormatter::FormatObjsAtFrame(SwFrame&, SwPageFrame const&, SwLayAction*) (objectformatter.cxx:191)
   by 0x41ADC213: SwLayAction::FormatContent(SwPageFrame const*) (layact.cxx:1633)
   by 0x41AD88DE: SwLayAction::InternalAction(OutputDevice*) (layact.cxx:760)
   by 0x41AD7080: SwLayAction::Action(OutputDevice*) (layact.cxx:351)
   by 0x41ADE32E: SwLayIdle::SwLayIdle(SwRootFrame*, SwViewShellImp*) (layact.cxx:2133)
   by 0x41FFC97E: SwViewShell::LayoutIdle() (viewsh.cxx:711)

Change-Id: I656cc2303eeccd5eef68ad3b8e81bb0fd47b94fb