name-rev: change ULONG_MAX to TIME_MAX

Earlier, dddbad7 ("timestamp_t: a new data type for timestamps",
2017-04-26) changed several types to timestamp_t.

5589e87 ("name-rev: change a "long" variable to timestamp_t",
2017-05-20) cleaned up a missed variable, but both missed a _MAX
constant.

Change the remaining constant to the one appropriate for the current
type

Signed-off-by: Michael J Gruber <git@grubix.eu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: mjg

builtin/name-rev.c

@@ -252,7 +252,7 @@ static int name_ref(const char *path, const struct object_id *oid, int flags, vo
 		struct commit *commit = (struct commit *)o;
 		int from_tag = starts_with(path, "refs/tags/");
 
-		if (taggerdate == ULONG_MAX)
+		if (taggerdate == TIME_MAX)
 			taggerdate = ((struct commit *)o)->date;
 		path = name_ref_abbrev(path, can_abbreviate_output);
 		name_rev(commit, xstrdup(path), taggerdate, 0, 0,