loongson/pypi: links for pcm2mp3

loongson/mirror pcm2mp3-1.8.tar.gz
loongson/mirror pcm2mp3-1.6.1.tar.gz
loongson/mirror pcm2mp3-1.5.5.tar.gz
loongson/mirror pcm2mp3-1.5.4.tar.gz
loongson/mirror pcm2mp3-1.5.2.tar.gz
loongson/mirror pcm2mp3-1.5.1.tar.gz
loongson/mirror pcm2mp3-1.5.0.tar.gz