Issue #19972: Add rarely used freefunc. This fixes a leak if sys.exit()

is used in a program.

Modules/_pickle.c

@@ -7464,6 +7464,12 @@ pickle_clear(PyObject *m)
     return 0;
 }
 
+static void
+pickle_free(PyObject *m)
+{
+    _Pickle_ClearState(_Pickle_GetState(m));
+}
+
 static int
 pickle_traverse(PyObject *m, visitproc visit, void *arg)
 {
@@ -7492,7 +7498,7 @@ static struct PyModuleDef _picklemodule = {
     NULL,                 /* m_reload */
     pickle_traverse,      /* m_traverse */
     pickle_clear,         /* m_clear */
-    NULL                 /* m_free */
+    (freefunc)pickle_free /* m_free */
 };
 
 PyMODINIT_FUNC