add codeSomeShardsP test
add codeSomeShardsP test

NicolasT/reedsolomon,somethingnew2-0/reedsolomon,fwessels/reedsolomon,NicolasT/reedsolomon,lukechampine/reedsolomon,klauspost/reedsolomon,justmao945/reedsolomon,beni55/reedsolomon