message: rpc: Remove unused PreCommand signal
diff: @@ -36,7 +36,6 @@ static struct CRPCSignals
  {
  boost::signals2::signal<void ()> Started;
  boost::signals2::signal<void ()> Stopped;
  - boost::signals2::signal<void (const CRPCCommand&)> PreCommand;
  } g_rpcSignals;
  void RPCServer::OnStarted(std::function<void ()> slot)
  @@ -484,8 +483,6 @@ UniValue CRPCTable::execute(const JSONRPCRequest &request) const
  if (!pcmd)
  throw JSONRPCError(RPC_METHOD_NOT_FOUND, "Method not found");
  - g_rpcSignals.PreCommand(*pcmd);
  -
  try
  {
  // Execute, convert arguments to array if necessary
  