[dev.power64] test: "fix" live.go test on power64x

On power64x, this one line in live.go reports that t is live
because of missing optimization passes.  This isn't what this
test is trying to test, so shuffle bad40 so that it still
accomplishes the intent of the test without also depending on
optimization.

LGTM=rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/167110043

test/live.go

@@ -614,8 +614,8 @@ func newT40() *T40 {
 
 func bad40() {
 	t := newT40()
-	println()
 	_ = t
+	println()
 }
 
 func good40() {