minor bench.c adjustments
minor bench.c adjustments

shorter debug messages
no need to check decompressedLength==0 twice

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