bpo-43269: Remove redundant extern keywords (GH-24605)

diff --git a/Modules/_sqlite/statement.c b/Modules/_sqlite/statement.c
index f179eee..5702627 100644
--- a/Modules/_sqlite/statement.c
+++ b/Modules/_sqlite/statement.c
@@ -480,7 +480,8 @@ static PyType_Spec stmt_spec = {
 };
 PyTypeObject *pysqlite_StatementType = NULL;
 
-extern int pysqlite_statement_setup_types(PyObject *module)
+int
+pysqlite_statement_setup_types(PyObject *module)
 {
     pysqlite_StatementType = (PyTypeObject *)PyType_FromModuleAndSpec(module, &stmt_spec, NULL);
     if (pysqlite_StatementType == NULL) {