added definitions for conversion constants, moved forced compression check to top of adaptCompressionLevel, used ZSTD_BLOCKSIZE_MAX
added definitions for conversion constants, moved forced compression check to top of adaptCompressionLevel, used ZSTD_BLOCKSIZE_MAX

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