string_list: Add STRING_LIST_INIT macro and make use of it.

Acked-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Thiago Farina <tfransosi@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/fetch.c b/builtin/fetch.c
index b0bfaa9..88ff357 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -548,8 +548,8 @@
 			struct ref **head,
 			struct ref ***tail)
 {
-	struct string_list existing_refs = { NULL, 0, 0, 0 };
-	struct string_list remote_refs = { NULL, 0, 0, 0 };
+	struct string_list existing_refs = STRING_LIST_INIT_NODUP;
+	struct string_list remote_refs = STRING_LIST_INIT_NODUP;
 	const struct ref *ref;
 	struct string_list_item *item = NULL;
 
@@ -651,7 +651,7 @@
 static int do_fetch(struct transport *transport,
 		    struct refspec *refs, int ref_count)
 {
-	struct string_list existing_refs = { NULL, 0, 0, 0 };
+	struct string_list existing_refs = STRING_LIST_INIT_NODUP;
 	struct string_list_item *peer_item = NULL;
 	struct ref *ref_map;
 	struct ref *rm;
@@ -874,7 +874,7 @@
 int cmd_fetch(int argc, const char **argv, const char *prefix)
 {
 	int i;
-	struct string_list list = { NULL, 0, 0, 0 };
+	struct string_list list = STRING_LIST_INIT_NODUP;
 	struct remote *remote;
 	int result = 0;