bpo-40750: Support -d flag in the new parser (GH-20340)

(cherry picked from commit 800a35c623bbcdb5793c7d7a4974524286311479)

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
diff --git a/Parser/pegen/pegen.h b/Parser/pegen/pegen.h
index 761e90f..bd3056e 100644
--- a/Parser/pegen/pegen.h
+++ b/Parser/pegen/pegen.h
@@ -72,6 +72,7 @@
     int feature_version;
     growable_comment_array type_ignore_comments;
     Token *known_err_token;
+    int level;
 } Parser;
 
 typedef struct {