test-date: drop unused parameter to getnanos()

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: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

t/helper/test-date.c

@@ -83,7 +83,7 @@ static void parse_approx_timestamp(const char **argv, struct timeval *now)
 	}
 }
 
-static void getnanos(const char **argv, struct timeval *now)
+static void getnanos(const char **argv)
 {
 	double seconds = getnanotime() / 1.0e9;
 
@@ -119,7 +119,7 @@ int cmd__date(int argc, const char **argv)
 	else if (!strcmp(*argv, "timestamp"))
 		parse_approx_timestamp(argv+1, &now);
 	else if (!strcmp(*argv, "getnanos"))
-		getnanos(argv+1, &now);
+		getnanos(argv+1);
 	else if (!strcmp(*argv, "is64bit"))
 		return sizeof(timestamp_t) == 8 ? 0 : 1;
 	else if (!strcmp(*argv, "time_t-is64bit"))