os: deflake TestFdReadRace by increasing timeout

This timeout will never be reached if the test passes, so it doesn't
much matter how long it is. The test is t.Parallel so on a slow system
1 second may occasionally not be enough, although on my laptop the
test takes about 0.02 seconds.

Fixes #34431

Change-Id: Ia2184e6be3747933bfe83aa6c8e1f77e6b1e0bba
Reviewed-on: https://go-review.googlesource.com/c/go/+/200764
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

src/os/pipe_test.go

@@ -428,7 +428,7 @@ func TestFdReadRace(t *testing.T) {
 	go func() {
 		defer wg.Done()
 		var buf [10]byte
-		r.SetReadDeadline(time.Now().Add(time.Second))
+		r.SetReadDeadline(time.Now().Add(time.Minute))
 		c <- true
 		if _, err := r.Read(buf[:]); os.IsTimeout(err) {
 			t.Error("read timed out")