If the destination buffer is the minimum allowed size in `ZSTD_compressSequences()` (2^17), then if the block isn't compressible compression might fail with `dstSize_tooSmall`, when it should instead emit a raw uncompressed block. Additionally, `ZSTD_compressLiterals()` implicitly called `ZSTD_noCompressLiterals()` if Huffman compression failed. Make that explicit.