Fix: zero whole object in GraalPyPrivate_Tuple_Alloc

Author: fangerer

graalpython/com.oracle.graal.python.cext/src/tupleobject.c

@@ -1326,12 +1326,19 @@ PyObject* GraalPyPrivate_Tuple_Alloc(PyTypeObject* type, Py_ssize_t nitems) {
     if (alloc  == NULL) {
         return PyErr_NoMemory();
     }
+
+    // GraalPy change: zero whole object
+    memset(alloc, '\0', size + presize);
+
     obj = (PyObject *)(alloc + presize);
     if (presize) {
-        // GraalPy change: different header layout, no GC link
-        ((PyObject **)alloc)[0] = NULL;
+        // GraalPy change: different header layout
+        // ((PyObject **)alloc)[0] = NULL;
+        // ((PyObject **)alloc)[1] = NULL;
+        _PyObject_GC_Link(obj);
     }
-    memset(obj, '\0', size);
+    // GraalPy change: whole memory is zero'd above
+    // memset(obj, '\0', size);
 
     if (type->tp_itemsize == 0) {
         _PyObject_Init(obj, type);