Derefedata length can be zero if there are no references in PPU

git-svn-id: trunk@32584 -

compiler/utils/ppuutils/ppudump.pp

@@ -860,7 +860,8 @@ begin
   derefdatalen:=ppufile.entrysize;
   if derefdatalen=0 then
     begin
-      WriteError('!! Error: derefdatalen=0');
+      Writeln(['No Derefdata length=0']);
+      derefdata:=nil;
       exit;
     end;
   Writeln(['Derefdata length: ',derefdatalen]);