tdf#130792 Draw crashes when trying to add a point in a multiline

regression from
    commit b4fc996520b47a6212661a9de3a1c72ccfc379a4
    loplugin:useuniqueptr in SdrHdlList
which changed SdrHdlList so that it crashes when passed a bad index.

I can't seem to fix the calling code without creating other regressions,
so just revert that part of the commit.

The calling code is in SdrDragView::ImpBegInsObjPoint where it calls
BegDragObj

Change-Id: I494baa9a2e815fd7b9532840b65483ba2a70bd42
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/93277
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
diff --git a/include/svx/svdhdl.hxx b/include/svx/svdhdl.hxx
index 4c77c94..ed29059 100644
--- a/include/svx/svdhdl.hxx
+++ b/include/svx/svdhdl.hxx
@@ -459,7 +459,7 @@ public:
    //          3.Level Position (x+y)
    void     Sort();
    size_t   GetHdlCount() const { return maList.size(); }
    SdrHdl*  GetHdl(size_t nNum) const { return maList[nNum].get(); }
    SdrHdl*  GetHdl(size_t nNum) const { return nNum < maList.size() ? maList[nNum].get() : nullptr; }
    size_t   GetHdlNum(const SdrHdl* pHdl) const;
    void     SetHdlSize(sal_uInt16 nSiz);
    sal_uInt16   GetHdlSize() const                        { return nHdlSize; }