message: Use DeploymentEnabled to hide VB deployments
  The helper was previously unused. This commit changes it to be more
  meaningful and puts it to use.
  See previous discussion at
diff: @@ -49,7 +49,7 @@ inline bool DeploymentEnabled(const Consensus::Params& params, Consensus::Buried
  inline bool DeploymentEnabled(const Consensus::Params& params, Consensus::DeploymentPos dep)
  {
  assert(Consensus::ValidDeployment(dep));
  - return params.vDeployments[dep].nTimeout != 0;
  + return params.vDeployments[dep].nStartTime != Consensus::BIP9Deployment::NEVER_ACTIVE;
  }
  #endif // BITCOIN_DEPLOYMENTSTATUS_H
  