Data race 2 via tx_pool

[holiman]

Detected via travis cron

WARNING: DATA RACE

Write at 0x00c000012778 by goroutine 87:

  sync/atomic.CompareAndSwapInt32()
      /home/travis/.gimme/versions/go1.19.1.linux.amd64/src/runtime/race_amd64.s:310 +0xb
  sync/atomic.CompareAndSwapInt32()
      <autogenerated>:1 +0x1e
  github.com/ethereum/go-ethereum/core.(*txNoncer).get()
      /home/travis/gopath/src/github.com/ethereum/go-ethereum/core/tx_noncer.go:48 +0x64
  github.com/ethereum/go-ethereum/core.(*TxPool).Nonce()
      /home/travis/gopath/src/github.com/ethereum/go-ethereum/core/tx_pool.go:466 +0x10f
  github.com/ethereum/go-ethereum/miner.(*testWorkerBackend).newRandomTx()
      /home/travis/gopath/src/github.com/ethereum/go-ethereum/miner/worker_test.go:194 +0x7d
  github.com/ethereum/go-ethereum/miner.testGenerateBlockAndImport()
      /home/travis/gopath/src/github.com/ethereum/go-ethereum/miner/worker_test.go:251 +0x8b7
  github.com/ethereum/go-ethereum/miner.TestGenerateBlockAndImportEthash()
      /home/travis/gopath/src/github.com/ethereum/go-ethereum/miner/worker_test.go:210 +0x30
  testing.tRunner()
      /home/travis/.gimme/versions/go1.19.1.linux.amd64/src/testing/testing.go:1446 +0x216
  testing.(*T).Run.func1()
      /home/travis/.gimme/versions/go1.19.1.linux.amd64/src/testing/testing.go:1493 +0x47

Previous write at 0x00c000012778 by goroutine 111:
  github.com/ethereum/go-ethereum/core.newTxNoncer()
      /home/travis/gopath/src/github.com/ethereum/go-ethereum/core/tx_noncer.go:37 +0xd64
  github.com/ethereum/go-ethereum/core.(*TxPool).reset()
      /home/travis/gopath/src/github.com/ethereum/go-ethereum/core/tx_pool.go:1291 +0xe1e
  github.com/ethereum/go-ethereum/core.(*TxPool).runReorg()
      /home/travis/gopath/src/github.com/ethereum/go-ethereum/core/tx_pool.go:1155 +0x373
  github.com/ethereum/go-ethereum/core.(*TxPool).scheduleReorgLoop.func2()
      /home/travis/gopath/src/github.com/ethereum/go-ethereum/core/tx_pool.go:1084 +0x71

func (txn *txNoncer) get(addr common.Address) uint64 {
	// We use mutex for get operation is the underlying
	// state will mutate db even for read access.
	txn.lock.Lock()                       <--- THIS LINE
	defer txn.lock.Unlock()

// newTxNoncer creates a new virtual state database to track the pool nonces.
func newTxNoncer(statedb *state.StateDB) *txNoncer {
	return &txNoncer{                      //  <--- PREVIOUS WRITE
		fallback: statedb.Copy(),
		nonces:   make(map[common.Address]uint64),
	}
}