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/_sqlite/row.c b/Modules/_sqlite/row.c
index 2fc26a8..3cfbeeb 100644
--- a/Modules/_sqlite/row.c
+++ b/Modules/_sqlite/row.c
@@ -150,7 +150,8 @@
     }
 }
 
-Py_ssize_t pysqlite_row_length(pysqlite_Row* self, PyObject* args, PyObject* kwargs)
+static Py_ssize_t
+pysqlite_row_length(pysqlite_Row* self)
 {
     return PyTuple_GET_SIZE(self->data);
 }