git: update to v2.17.1

Update to git version v2.17.1. Required changes:

* The function 'typename' has been renamed to 'type_name'
  (upstream commit debca9d2fe784193dc2d9f98b5edac605ddfefbb)

Signed-off-by: Christian Hesse <mail@eworm.de>

ui-shared.c

@@ -545,7 +545,7 @@ void cgit_object_link(struct object *obj)
 		page = "tag";
 	else
 		page = "blob";
-	name = fmt("%s %s...", typename(obj->type), shortrev);
+	name = fmt("%s %s...", type_name(obj->type), shortrev);
 	reporevlink(page, name, NULL, NULL, ctx.qry.head, fullrev, NULL);
 }