fixed missing output of internal DTD param entities when nothing else

* tree.c: fixed missing output of internal DTD param entities when
  nothing else present in DTD (bug 134052)
diff --git a/tree.c b/tree.c
index 620768b..5a6c9df 100644
--- a/tree.c
+++ b/tree.c
@@ -7370,7 +7370,8 @@
 	xmlBufferWriteQuotedString(buf->buffer, dtd->SystemID);
     }
     if ((dtd->entities == NULL) && (dtd->elements == NULL) &&
-        (dtd->attributes == NULL) && (dtd->notations == NULL)) {
+            (dtd->attributes == NULL) && (dtd->notations == NULL) &&
+	    (dtd->pentities == NULL)) {
 	xmlOutputBufferWriteString(buf, ">");
 	return;
     }