[Bug]:A potential goroutine leak

[xuxiaofan1203]

Hello @samuelkarp, When I used fifo, I found a potential bug, I'm not sure, maybe we can discuss to avoid a goleak
blocking position:

fifo/fifo.go

Lines 124 to 133 in 3e17f98

	select {
	case <-ctx.Done():
	select {
	case <-f.opened:
	default:
	f.Close()
	}
	case <-f.opened:
	case <-f.closed:
	}

if users use the OpenFilo() with the parameters like this:
f, err := OpenFifo(context.Background(), filepath.Join(tmpdir, "f0"), syscall.O_RDONLY|syscall.O_CREAT|syscall.O_NONBLOCK, 0600)
The select statement will block beacuse there is no cancelFunc to awaken the <-ctx.Done().

I wrote a test function to reproduce the bug considering the test that

fifo/fifo_test.go

Line 47 in 3e17f98

func TestFifoCancel(t *testing.T) {

func TestFifoNocancel(t *testing.T) {
	defer goleak.VerifyNone(t)
	tmpdir, err := os.MkdirTemp("", "fifos")
	assert.NoError(t, err)
	defer os.RemoveAll(tmpdir)

	leakCheckWg = &sync.WaitGroup{}
	defer func() {
		leakCheckWg = nil
	}()

	//f, err := OpenFifo(context.Background(), filepath.Join(tmpdir, "f0"), syscall.O_RDONLY|syscall.O_NONBLOCK, 0600)
	f, err := OpenFifo(context.Background(), filepath.Join(tmpdir, "f0"), syscall.O_RDONLY|syscall.O_CREAT|syscall.O_NONBLOCK, 0600)
	assert.Exactly(t, nil, f)
	assert.NotNil(t, err)
	assert.NoError(t, checkWgDone(leakCheckWg))
}

The test result shows it is a goroutine leak, you can use goleak to reproduce the bug.