bpo-33029: Fix signatures of getter and setter functions. (GH-10746)

Fix also return type for few other functions (clear, releasebuffer).
diff --git a/Modules/_io/bytesio.c b/Modules/_io/bytesio.c
index 8e54ec8..55e34c6 100644
--- a/Modules/_io/bytesio.c
+++ b/Modules/_io/bytesio.c
@@ -202,7 +202,7 @@
 }
 
 static PyObject *
-bytesio_get_closed(bytesio *self)
+bytesio_get_closed(bytesio *self, void *Py_UNUSED(ignored))
 {
     if (self->buf == NULL) {
         Py_RETURN_TRUE;