py: Implement proper re-raising in native codegen's finally handler.

This allows an exception to propagate correctly through a finally
handler.
diff --git a/py/runtime.h b/py/runtime.h
index ce87bf0..1216462 100644
--- a/py/runtime.h
+++ b/py/runtime.h
@@ -119,7 +119,7 @@
 mp_uint_t mp_convert_obj_to_native(mp_obj_t obj, mp_uint_t type);
 mp_obj_t mp_convert_native_to_obj(mp_uint_t val, mp_uint_t type);
 mp_obj_t mp_native_call_function_n_kw(mp_obj_t fun_in, mp_uint_t n_args_kw, const mp_obj_t *args);
-NORETURN void mp_native_raise(mp_obj_t o);
+void mp_native_raise(mp_obj_t o);
 
 extern struct _mp_obj_list_t mp_sys_path_obj;
 extern struct _mp_obj_list_t mp_sys_argv_obj;