Missing intialization of SwPageDesc::m_pTextFormatColl

...in efcb9a70 "use sw::WriterMultiListener
instead of SwDepend in SwPageDesc", causing

> /sw/source/core/layout/pagedesc.cxx:198:74: runtime error: upcast of misaligned address 0xbebebebebebebebe for type 'SwTextFormatColl', which requires 8 byte alignment
> 0xbebebebebebebebe: note: pointer points here
> <memory cannot be printed>
>     #0 0x2b06bea9116b in SwPageDesc::GetRegisterFormatColl() const /sw/source/core/layout/pagedesc.cxx:198:74

during e.g. CppunitTest_sw_odfimport of ASan+UBSan builds.

Change-Id: If50a920ca5dafdce6c1a3e2fbf540488685e641a

sw/source/core/layout/pagedesc.cxx

@@ -46,6 +46,7 @@ SwPageDesc::SwPageDesc(const OUString& rName, SwFrameFormat *pFormat, SwDoc *con
     , m_FirstMaster( pDoc->GetAttrPool(), rName, pFormat )
     , m_FirstLeft( pDoc->GetAttrPool(), rName, pFormat )
     , m_aDepends(*this)
+    , m_pTextFormatColl(nullptr)
     , m_pFollow( this )
     , m_nRegHeight( 0 )
     , m_nRegAscent( 0 )