strftime_ns
(void)strftime_ns(buf, sizeof(buf), format, lt,
(void)strftime_ns(buf, sizeof(buf), fmtbuf, lt, nsec, res);
(void)strftime_ns(tzbuf, sizeof(tzbuf), "%z", lt, nsec, res);
static size_t strftime_ns(char * __restrict, size_t, const char * __restrict,