tdf#117539 Crash after cut and paste operation of a chart stick

regression from
   commit 3d44b720f5
   loplugin:useuniqueptr in SfxItemPool_Impl
where I accidentally removed some fallback code.

Note that this does not fix the underlying bug where some pool is not
correctly set up.

Also, this only fixes the bug that I introduced in the above commit,
another bug in the same area has subsequently been introduced, causing
a crash in a different area when performing this operation.

Change-Id: Iaae3b0dc82c740b498e3735273820647ef28fd01
Reviewed-on: https://gerrit.libreoffice.org/54522
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

svl/source/items/itemset.cxx

@@ -94,6 +94,12 @@ SfxItemSet::SfxItemSet(SfxItemPool& rPool)
 {
     m_pWhichRanges = const_cast<sal_uInt16*>(m_pPool->GetFrozenIdRanges());
     assert( m_pWhichRanges && "don't create ItemSets with full range before FreezeIdRanges()" );
+    if (!m_pWhichRanges)
+    {
+        std::unique_ptr<sal_uInt16[]> tmp;
+        m_pPool->FillItemIdRanges_Impl(tmp);
+        m_pWhichRanges = tmp.release();
+    }
 
     const sal_uInt16 nSize = TotalCount();
     m_pItems.reset(new const SfxPoolItem*[nSize]{});