testsuite: Add an xfailed test case for the new `extern mod` syntax

src/test/run-pass/extern-mod-url.rs

@@ -0,0 +1,16 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Just a test that new-style extern mods parse
+
+// xfail-test
+extern mod test = "github.com/catamorphism/test-pkg";
+
+fn main() {}