fdo#39003: fix autoformat Undo cursors:

SwEditShell::Undo: Because the Undo actions nowadays create new shell
cursors directly (while previously they worked on a SwUndoIter), it is
necessary to remove the shell cursor ring before Pop() because Pop(false)
only restores the current cursor from the stack, not the rest of the ring.
(regression from CWS undoapi, 1ba0c187)

sw/source/core/edit/edundo.cxx

@@ -142,6 +142,10 @@ bool SwEditShell::Undo(sal_uInt16 const nCount)
                     .getStr());
         }
 
+        if (bRestoreCrsr)
+        {   // fdo#39003 Pop does not touch the rest of the cursor ring
+            KillPams(); // so call this first to get rid of unwanted cursors
+        }
         Pop( !bRestoreCrsr );
 
         GetDoc()->SetRedlineMode( eOld );