cmd/compile: replace range loop over list of nodes with orderexprlistinplace

Replace explicit range loop that applies orderexprinplace on a
list of nodes with existing helper function orderexprlistinplace.

Passes toolstash -cmp.

Change-Id: Ic8098ed08cf67f319de3faa83b00a5b73bbde95d
Reviewed-on: https://go-review.googlesource.com/88815Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/gc/order.go

@@ -762,9 +762,7 @@ func orderstmt(n *Node, order *Order) {
 			// hiter contains pointers and needs to be zeroed.
 			prealloc[n] = ordertemp(hiter(n.Type), order, true)
 		}
-		for i, n1 := range n.List.Slice() {
-			n.List.SetIndex(i, orderexprinplace(n1, order))
-		}
+		orderexprlistinplace(n.List, order)
 		orderblockNodes(&n.Nbody)
 		order.out = append(order.out, n)
 		cleantemp(t, order)