ZSTD_deriveBlockSplitsHelper
ZSTD_deriveBlockSplitsHelper(splits, startIdx, midIdx, zc, origSeqStore);
ZSTD_deriveBlockSplitsHelper(splits, midIdx, endIdx, zc, origSeqStore);
ZSTD_deriveBlockSplitsHelper(&splits, 0, nbSeq, zc, &zc->seqStore);