Make two PyModuleDef_Slot symbols static in _testmultiphase. (pythonGH-8147)

(cherry picked from commit cb4bae7)

Co-authored-by: Benjamin Peterson <[email protected]>

Author: benjaminp

Modules/_testmultiphase.c

@@ -237,7 +237,7 @@ static int execfunc(PyObject *m)
 
 #define TEST_MODULE_DEF(name, slots, methods) TEST_MODULE_DEF_EX(name, slots, methods, 0, NULL)
 
-PyModuleDef_Slot main_slots[] = {
+static PyModuleDef_Slot main_slots[] = {
     {Py_mod_exec, execfunc},
     {0, NULL},
 };
@@ -487,7 +487,7 @@ createfunc_null(PyObject *spec, PyModuleDef *def)
     return NULL;
 }
 
-PyModuleDef_Slot slots_create_null[] = {
+static PyModuleDef_Slot slots_create_null[] = {
     {Py_mod_create, createfunc_null},
     {0, NULL},
 };