(my_strftime): Define to nstrftime if emacs, but only if my_strftime is not defined. (extra_args, extra_args_spec, extra_args_spec_iso): Rename from ut_argument, ut_argument_spec, ut_argument_spec_iso, respectively. Add one more extra argument: a nanoseconds value. All uses changed. (ns): New macro. (my_strftime function): Add %N format. (emacs_strftimeu): Renamed from emacs_strftime, with extra ut argument.