Fix DocumentRedlineManager code that crashes Writer.

One of my document crashes Writer when I delete one table row, with
change tracking enabled. I observed that in DeleteRedline(),
either Start or End of the SwRangeRedline object has been changed
so that it breaks the order of SwRedlineTable.

Change-Id: I6e477488a894996dea4efb433eb3e03edf5fd26d
Reviewed-on: https://gerrit.libreoffice.org/15002Tested-by: Caolán McNamara <caolanm@redhat.com>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>

sw/source/core/doc/DocumentRedlineManager.cxx

@@ -1973,7 +1973,7 @@ bool DocumentRedlineManager::DeleteRedline( const SwPaM& rRange, bool bSaveInUnd
                     if( !pRedl->HasValidRange() )
                     {
                         // re-insert
-                        mpRedlineTbl->Remove( pRedl );
+                        mpRedlineTbl->Remove( n );
                         mpRedlineTbl->Insert( pRedl );
                         --n;
                     }