cmd/compile: stop exporting OPTRLIT

Removes TODO left by previous commit to appease toolstash.

Change-Id: I5c0bf25f21ba5c0abe3b1b2ed0b17c604717f39b
Reviewed-on: https://go-review.googlesource.com/c/go/+/197121Reviewed-by: Robert Griesemer <gri@golang.org>

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

@@ -1181,10 +1181,9 @@ func (w *exportWriter) expr(n *Node) {
 	// 	should have been resolved by typechecking - handled by default case
 
 	case OPTRLIT:
-		w.op(OPTRLIT) // TODO(mdempsky): Replace with OADDR.
+		w.op(OADDR)
 		w.pos(n.Pos)
 		w.expr(n.Left)
-		w.bool(false)
 
 	case OSTRUCTLIT:
 		w.op(OSTRUCTLIT)

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

@@ -801,10 +801,8 @@ func (r *importReader) node() *Node {
 	// case OCLOSURE:
 	//	unimplemented
 
-	case OPTRLIT:
-		n := nodl(r.pos(), OADDR, r.expr(), nil)
-		_ = r.bool()
-		return n
+	// case OPTRLIT:
+	//	unreachable - mapped to case OADDR below by exporter
 
 	case OSTRUCTLIT:
 		// TODO(mdempsky): Export position information for OSTRUCTKEY nodes.