asn1: marshal true as 255, not 1.

OS X, at least, appears to test |byte == 255|, not |byte != 0| to
establish if a bool is true or false.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/4128064

src/pkg/asn1/marshal.go

@@ -317,7 +317,7 @@ func marshalBody(out *forkableWriter, value reflect.Value, params fieldParameter
 	switch v := value.(type) {
 	case *reflect.BoolValue:
 		if v.Get() {
-			return out.WriteByte(1)
+			return out.WriteByte(255)
 		} else {
 			return out.WriteByte(0)
 		}