Don't leave sdr::table::Cell members implicitly declared

...otherwise, as the class is SVX_DLLPUBLIC and---for better or worse---
SVX_DLLPUBLIC is shared between Library_svxcore and Library_svxcore, all .cxx in
Library_svx that happen to include cell.hxx would emit them (as well as those in
Library_svxcore, of course), and the copy ctor requires the vtable, which in
turn requires an adjustor thunk for Cell::getPropertyStates, which happens to
not be emitted into any of the Library_svx .cxx that require it under clang-cl
due to <https://llvm.org/bugs/show_bug.cgi?id=25641> "clang-cl: vtordisp thunks
not emitted for functions with class template specializations in their
signatures."

Change-Id: Ib03b7002f9dfe3c2df742640ef7406cf24a7cecd

svx/source/table/cell.hxx

@@ -206,6 +206,9 @@ private:
     SVX_DLLPRIVATE Cell( SdrTableObj& rTableObj, OutlinerParaObject* pOutlinerParaObject ) throw(css::uno::RuntimeException);
     SVX_DLLPRIVATE virtual ~Cell() throw();
 
+    Cell(Cell const &) = delete;
+    void operator =(Cell const &) = delete;
+
     const SvxItemPropertySet* mpPropSet;
 
     sdr::properties::TextProperties*    mpProperties;