Resolves: fdo#88721 correct negated condition in range name validation

Fallout of 72b9dd27 String to OUString
conversion.

Change-Id: I89a90da11790efba9e8ce4c9464dfca50b08c3ce

sc/source/core/tool/rangenam.cxx

@@ -461,7 +461,7 @@ void ScRangeData::MakeValidName( OUString& rName )
         {
             // Range Parse is partially valid also with invalid sheet name,
             // Address Parse dito, during compile name would generate a #REF!
-            if ( rName.indexOf( '.' ) == -1 )
+            if ( rName.indexOf( '.' ) != -1 )
                 rName = rName.replaceFirst( ".", "_" );
             else
                 rName = "_" + rName;