test: add test case for issue #13248

Issue #13248 was fixed by https://go-review.googlesource.com/#/c/16930/.
This is the corresponding test case (original offending program).

Change-Id: I7c99783db74a5422704409cea7e5073094beadd3
Reviewed-on: https://go-review.googlesource.com/16973
Reviewed-by: Chris Manghane <cmang@golang.org>

test/fixedbugs/issue13248.go

@@ -0,0 +1,13 @@
+// errorcheck
+
+// Copyright 2015 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.
+
+// This program caused an infinite loop with the recursive-descent parser.
+
+package main
+
+func main() {
+    foo(
+} // ERROR "unexpected }"