Remove Boost Pointer Container Library related functions

...no longer used since the last boost:ptr_vector<SvLBoxItem> has been removed
in 63de1888 "svtools: replace boost::ptr_vector
with std::vector<std::unique_ptr>"

Change-Id: Icd5e9671bb79b0bb2e3b12ef004ac9ec112981f8

include/svtools/treelistbox.hxx

@@ -177,18 +177,6 @@ public:
     virtual void        Clone(SvLBoxItem* pSource) = 0;
 };
 
-inline SvLBoxItem* new_clone(const SvLBoxItem& rSrc)
-{
-    SvLBoxItem* p = rSrc.Create();
-    p->Clone(const_cast<SvLBoxItem*>(&rSrc));
-    return p;
-}
-
-inline void delete_clone(const SvLBoxItem* p)
-{
-    delete p;
-}
-
 // *********************************************************************
 // ****************************** SvTreeListBox ************************
 // *********************************************************************