loongson/pypi: links for bitfield

loongson/mirror bitfield-1.32.tar.gz
loongson/mirror bitfield-1.31.tar.gz
loongson/mirror bitfield-1.3.tar.gz
loongson/mirror bitfield-1.2.tar.gz
loongson/mirror bitfield-1.1.tar.gz
loongson/mirror bitfield-1.0.tar.gz