Fix regression where we stopped closing scenes on simulator exit.

If we don't do this, then these scenes don't get deregistered from the grid, amongst other things.
Regression was introduced in commit 8c130bc (Mon Nov 12 22:50:28 2012 +0000)

OpenSim/Region/Framework/Scenes/SceneManager.cs

@@ -141,6 +141,13 @@ namespace OpenSim.Region.Framework.Scenes
 
         public void Close()
         {
+            lock (m_localScenes)
+            {
+                for (int i = 0; i < m_localScenes.Count; i++)
+                {
+                    m_localScenes[i].Close();
+                }
+            }
         }
 
         public void Close(Scene cscene)