all: remove redundant string conversions when formatting []byte with %s

Change-Id: I603051a3174b139ffb81d20d42979c7f3f04a09a
Reviewed-on: https://go-review.googlesource.com/c/go/+/521136
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: shuang cui <imcusg@gmail.com>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/bytes/example_test.go

@@ -81,9 +81,9 @@ func ExampleBuffer_Next() {
 	var b bytes.Buffer
 	b.Grow(64)
 	b.Write([]byte("abcde"))
-	fmt.Printf("%s\n", string(b.Next(2)))
-	fmt.Printf("%s\n", string(b.Next(2)))
-	fmt.Printf("%s", string(b.Next(2)))
+	fmt.Printf("%s\n", b.Next(2))
+	fmt.Printf("%s\n", b.Next(2))
+	fmt.Printf("%s", b.Next(2))
 	// Output:
 	// ab
 	// cd

src/crypto/rsa/example_test.go

@@ -78,7 +78,7 @@ func ExampleDecryptPKCS1v15SessionKey() {
 		return
 	}
 
-	fmt.Printf("Plaintext: %s\n", string(plaintext))
+	fmt.Printf("Plaintext: %s\n", plaintext)
 }
 
 func ExampleSignPKCS1v15() {
@@ -149,7 +149,7 @@ func ExampleDecryptOAEP() {
 		return
 	}
 
-	fmt.Printf("Plaintext: %s\n", string(plaintext))
+	fmt.Printf("Plaintext: %s\n", plaintext)
 
 	// Remember that encryption only provides confidentiality. The
 	// ciphertext should be signed before authenticity is assumed and, even

src/runtime/testdata/testprogcgo/numgoroutine.go

@@ -70,7 +70,7 @@ func checkNumGoroutine(label string, want int) (string, bool) {
 	sbuf = sbuf[:runtime.Stack(sbuf, true)]
 	n = strings.Count(string(sbuf), "goroutine ")
 	if n != want {
-		fmt.Printf("%s Stack: want %d; got %d:\n%s\n", label, want, n, string(sbuf))
+		fmt.Printf("%s Stack: want %d; got %d:\n%s\n", label, want, n, sbuf)
 		return "", false
 	}
 	return string(sbuf), true