Print cdifficulty and don't serialize miner tx hash twice

src/daemon/rpc_command_executor.cpp

@@ -92,6 +92,7 @@ namespace {
       << "depth: " << boost::lexical_cast<std::string>(header.depth) << std::endl
       << "hash: " << header.hash << std::endl
       << "difficulty: " << header.wide_difficulty << std::endl
+      << "cumulative difficulty: " << header.wide_cumulative_difficulty << std::endl
       << "POW hash: " << header.pow_hash << std::endl
       << "block size: " << header.block_size << std::endl
       << "block weight: " << header.block_weight << std::endl

src/rpc/core_rpc_server.cpp

@@ -1950,7 +1950,6 @@ namespace cryptonote
       error_resp.message = "Internal error: can't produce valid response.";
       return false;
     }
-    res.miner_tx_hash = epee::string_tools::pod_to_hex(cryptonote::get_transaction_hash(blk.miner_tx));
     for (size_t n = 0; n < blk.tx_hashes.size(); ++n)
     {
       res.tx_hashes.push_back(epee::string_tools::pod_to_hex(blk.tx_hashes[n]));