tdf#105182 sd: avoid iterating too far in SdOutliner::Initialize()

Considering the valid indexes are extended by "-1" for backwards
iterators and "size()" for forward iterators, it's obvious that a
not-yet-at-the-end-in-the-other-direction iterator can be incremented
once, but not necessarily twice.

Why this code even wants to increment it twice isn't obvious to me.

Change-Id: I578c8c6202049ebe6dbed41b8276a6bfa0566bbc

sd/source/ui/view/Outliner.cxx

@@ -583,7 +583,10 @@ void SdOutliner::Initialize (bool bDirectionIsForward)
             // The iterator has pointed to the object one ahead/before the current
             // one.  Now move it to the one before/ahead the current one.
             ++maObjectIterator;
-            ++maObjectIterator;
+            if (maObjectIterator != sd::outliner::OutlinerContainer(this).end())
+            {
+                ++maObjectIterator;
+            }
         }
 
         mbMatchMayExist = true;