string_list: Fix argument order for string_list_append

Update the definition and callers of string_list_append to use the
string_list as the first argument.  This helps make the string_list
API easier to use by being more consistent.

Signed-off-by: Julian Phillips <julian@quantumfyre.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/remote.c b/remote.c
index 5a65838..9f0c6ef 100644
--- a/remote.c
+++ b/remote.c
@@ -1711,7 +1711,7 @@
 	info.ref_names = &ref_names;
 	info.stale_refs_tail = &stale_refs;
 	for (ref = fetch_map; ref; ref = ref->next)
-		string_list_append(ref->name, &ref_names);
+		string_list_append(&ref_names, ref->name);
 	sort_string_list(&ref_names);
 	for_each_ref(get_stale_heads_cb, &info);
 	string_list_clear(&ref_names, 0);