gh-160245: Reduce padding in the Memo struct in the parser (#160266)

Author: ashm-dev

Misc/NEWS.d/next/Core_and_Builtins/2026-10-22-14-45-00.gh-issue-160245.mEmO24.rst

@@ -0,0 +1,2 @@
+Reduce the size of parser memo entries on 64-bit platforms by reordering
+fields to remove padding. Patch by Shamil Abdulaev.

Parser/pegen.h

@@ -31,8 +31,8 @@
 
 typedef struct _memo {
     int type;
-    void *node;
     int mark;
+    void *node;
     struct _memo *next;
 } Memo;