Here is a patch for timemodule.c. I have converted everything except: 

* ctime() uses the gettmarg() function. Converting gettmarg() itself doesn't seem possible to me (because it's not Python callable), and duplicating the functionality in a single complicated clinic section just for ctime() did not seem reasonable either.

* gmtime(), localtime(), ctime() use a the parse_time_t_args() utility function. I have not yet figured out how to replace this with argument clinic (sent a mail to python-dev about that).