loongson/mirror: links for pipestack

loongson/mirror PipeStack-0.5.3.tar.gz
loongson/mirror PipeStack-0.5.2.tar.gz
loongson/mirror PipeStack-0.5.1.tar.gz
loongson/mirror PipeStack-0.5.0.tar.gz
loongson/mirror PipeStack-0.4.0.tar.gz