string_list: use string-list API in unsorted_string_list_lookup()

Using the string-list API in function unsorted_string_list_lookup()
makes the code more readable.

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: ralfth

string-list.c

@@ -231,12 +231,12 @@ void string_list_sort(struct string_list *list)
 struct string_list_item *unsorted_string_list_lookup(struct string_list *list,
 						     const char *string)
 {
-	int i;
+	struct string_list_item *item;
 	compare_strings_fn cmp = list->cmp ? list->cmp : strcmp;
 
-	for (i = 0; i < list->nr; i++)
-		if (!cmp(string, list->items[i].string))
-			return list->items + i;
+	for_each_string_list_item(item, list)
+		if (!cmp(string, item->string))
+			return item;
 	return NULL;
 }