message: fix: remove update parameter from worker.commit
  With empty block mining logic totally removed in the prior commit,
  worker.commit is now only called with update=true. We can now safely
  remove the argument and the affected codepaths.
diff: @@ -457,7 +457,7 @@ func (w *worker) mainLoop() {
  uncles = append(uncles, uncle.Header())
  return false
  })
  - w.commit(uncles, nil, true, start)
  + w.commit(uncles, nil, start)
  }
  }
  // Read from the sync service and mine single txs
  @@ -955,7 +955,7 @@ func (w *worker) commitNewTx(tx *types.Transaction) error {
  if w.commitTransactions(txs, w.coinbase, nil) {
  return errors.New("Cannot commit transaction in miner")
  }
  - return w.commit(nil, w.fullTaskHook, true, tstart)
  + return w.commit(nil, w.fullTaskHook, tstart)
  }
  // commitNewWork generates several new sealing tasks based on the parent block.
  @@ -1066,12 +1066,12 @@ func (w *worker) commitNewWork(interrupt *int32, timestamp int64) {
  return
  }
  }
  - w.commit(uncles, w.fullTaskHook, true, tstart)
  + w.commit(uncles, w.fullTaskHook, tstart)
  }
  // commit runs any post-transaction state modifications, assembles the final block
  // and commits new work if consensus engine is running.
  -func (w *worker) commit(uncles []*types.Header, interval func(), update bool, start time.Time) error {
  +func (w *worker) commit(uncles []*types.Header, interval func(), start time.Time) error {
  // Deep copy receipts here to avoid interaction between different tasks.
  receipts := make([]*types.Receipt, len(w.current.receipts))
  for i, l := range w.current.receipts {
  @@ -1115,9 +1115,7 @@ func (w *worker) commit(uncles []*types.Header, interval func(), update bool, st
  log.Info("Worker has exited")
  }
  }
  - if update {
  w.updateSnapshot()
  - }
  return nil
  }
  