src: Use bytes.Equal instead of bytes.Compare where possible.

bytes.Equal is simpler to read and should also be faster because
of short-circuiting and assembly implementations.

Change generated automatically using:
  gofmt -r 'bytes.Compare(a, b) == 0 -> bytes.Equal(a, b)'
  gofmt -r 'bytes.Compare(a, b) != 0 -> !bytes.Equal(a, b)'

R=golang-dev, dave, adg, rsc
CC=golang-dev
https://golang.org/cl/7038051
diff --git a/src/pkg/math/big/int_test.go b/src/pkg/math/big/int_test.go
index fd6d152..6c981e7 100644
--- a/src/pkg/math/big/int_test.go
+++ b/src/pkg/math/big/int_test.go
@@ -643,7 +643,7 @@
 
 func checkBytes(b []byte) bool {
 	b2 := new(Int).SetBytes(b).Bytes()
-	return bytes.Compare(b, b2) == 0
+	return bytes.Equal(b, b2)
 }
 
 func TestBytes(t *testing.T) {