loongson/mirror: links for spans-and-trees

loongson/mirror spans_and_trees-0.1.4.tar.gz
loongson/mirror spans_and_trees-0.1.3.tar.gz
loongson/mirror spans_and_trees-0.1.2.tar.gz
loongson/mirror spans_and_trees-0.1.1.tar.gz
loongson/mirror spans_and_trees-0.1.0.tar.gz