The getnanos() helper always gets the current time from our
getnanotime() facility. The caller cannot override it via TEST_DATE_NOW,
and hence we simply ignore the "now" parameter to the function. Let's
remove it, as it may mislead callers into thinking it does something.
Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>