bpo-33677: Fix signatures of tp_clear handlers for AST and deque.

Modules/_collectionsmodule.c

@@ -575,7 +575,7 @@ deque_concat(dequeobject *deque, PyObject *other)
     return new_deque;
 }
 
-static void
+static int
 deque_clear(dequeobject *deque)
 {
     block *b;
@@ -587,7 +587,7 @@ deque_clear(dequeobject *deque)
     PyObject **itemptr, **limit;
 
     if (Py_SIZE(deque) == 0)
-        return;
+        return 0;
 
     /* During the process of clearing a deque, decrefs can cause the
        deque to mutate.  To avoid fatal confusion, we have to make the
@@ -648,14 +648,15 @@ deque_clear(dequeobject *deque)
     }
     CHECK_END(leftblock->rightlink);
     freeblock(leftblock);
-    return;
+    return 0;
 
   alternate_method:
     while (Py_SIZE(deque)) {
         item = deque_pop(deque, NULL);
         assert (item != NULL);
         Py_DECREF(item);
     }
+    return 0;
 }
 
 static PyObject *

Parser/asdl_c.py

@@ -647,10 +647,11 @@ def visitModule(self, mod):
     return 0;
 }
 
-static void
+static int
 ast_clear(AST_object *self)
 {
     Py_CLEAR(self->dict);
+    return 0;
 }
 
 static int

Python/Python-ast.c

@@ -533,10 +533,11 @@ ast_traverse(AST_object *self, visitproc visit, void *arg)
     return 0;
 }
 
-static void
+static int
 ast_clear(AST_object *self)
 {
     Py_CLEAR(self->dict);
+    return 0;
 }
 
 static int