message: replace the now removed CSharedUnlocker with manual locking/unlocking
diff: @@ -747,6 +747,9 @@ bool ProcessMessage(CNode *pfrom, std::string strCommand, CDataStream &vRecv, in
  // messages during the initial (x)version handshake).
  else if (strCommand == NetMsgType::PING)
  {
  + LeaveCritical(&pfrom->csMsgSerializer);
  + EnterCritical("pfrom.csMsgSerializer", __FILE__, __LINE__, (void *)(&pfrom->csMsgSerializer), LockType::SHARED_MUTEX,
  + OwnershipType::EXCLUSIVE);
  uint64_t nonce = 0;
  vRecv >> nonce;
  // although PONG was enabled in BIP31, all clients should handle it at this point
  @@ -763,6 +766,9 @@ bool ProcessMessage(CNode *pfrom, std::string strCommand, CDataStream &vRecv, in
  // seconds to respond to each, the 5th ping the remote sends would appear to
  // return very quickly.
  pfrom->PushMessage(NetMsgType::PONG, nonce);
  + LeaveCritical(&pfrom->csMsgSerializer);
  + EnterCritical("pfrom.csMsgSerializer", __FILE__, __LINE__, (void *)(&pfrom->csMsgSerializer), LockType::SHARED_MUTEX,
  + OwnershipType::SHARED);
  }
  // ------------------------- END INITIAL COMMAND SET PROCESSING
  