also test syntax package

Change-Id: I41098d8c1f0aa4beb4098c7ade475807c80ab0af

Author: mateusz834

src/cmd/compile/internal/syntax/testdata/issue70957.go

@@ -0,0 +1,9 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func f() { goto /* ERROR syntax error: unexpected semicolon, expected name */ ;}
+
+func f() { goto } // ERROR syntax error: unexpected }, expected name