message: Don't update the block time for PoS
diff: @@ -233,6 +233,7 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& sc
  // Fill in header
  pblock->hashPrevBlock = pindexPrev->GetBlockHash();
  + if (!fProofOfStake)
  UpdateTime(pblock, chainparams.GetConsensus(), pindexPrev);
  pblock->nBits = GetNextWorkRequired(pindexPrev, pblock, chainparams.GetConsensus());
  pblock->nNonce = 0;
  