cmd/stringer: fix typo in test log message ("no" -> "not")

Fixes golang/go#22623

Change-Id: I62ab82a04f34f379f715f0902a69caa9c74c50d2
Reviewed-on: https://go-review.googlesource.com/76397
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Kevin Burke <kev@inburke.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/cmd/stringer/endtoend_test.go b/cmd/stringer/endtoend_test.go
index a1db27a..273f29b 100644
--- a/cmd/stringer/endtoend_test.go
+++ b/cmd/stringer/endtoend_test.go
@@ -54,7 +54,7 @@
 			continue
 		}
 		if name == "cgo.go" && !build.Default.CgoEnabled {
-			t.Logf("cgo is no enabled for %s", name)
+			t.Logf("cgo is not enabled for %s", name)
 			continue
 		}
 		// Names are known to be ASCII and long enough.