Replace some calls to die(usage_str) with usage(usage_str).

The only change in behaviour should be having a "usage: " prefix
on the output string rather than "fatal: ", and an exit code of
129 rather than 128.

Signed-off-by: Ramsay Allan Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/hash-object.c b/hash-object.c
index 43bd93b..5f89e64 100644
--- a/hash-object.c
+++ b/hash-object.c
@@ -46,7 +46,7 @@
 		if (!no_more_flags && argv[i][0] == '-') {
 			if (!strcmp(argv[i], "-t")) {
 				if (argc <= ++i)
-					die(hash_object_usage);
+					usage(hash_object_usage);
 				type = argv[i];
 			}
 			else if (!strcmp(argv[i], "-w")) {
@@ -66,8 +66,8 @@
 				hash_stdin(type, write_object);
 			}
 			else
-				die(hash_object_usage);
-		} 
+				usage(hash_object_usage);
+		}
 		else {
 			const char *arg = argv[i];
 			if (0 <= prefix_length)