removed zstdmt generation from Appveyor artefact build
removed zstdmt generation from Appveyor artefact build

Cyan4973/zstd,Majlen/zstd,Majlen/zstd,Majlen/zstd,Cyan4973/zstd,Cyan4973/zstd,Cyan4973/zstd,Majlen/zstd,Cyan4973/zstd