auto merge of #12927 : sfackler/rust/test-warn, r=huonw

The use of `std::os::args` creates a deprecated_owned_vector warning
with a bogus span.

Author: bors

src/librustc/front/test.rs

@@ -329,6 +329,7 @@ fn mk_test_module(cx: &TestCtxt) -> @ast::Item {
     // with our list of tests
     let mainfn = (quote_item!(&cx.ext_cx,
         pub fn main() {
+            #[allow(deprecated_owned_vector)];
             #[main];
             test::test_main_static(::std::os::args(), TESTS);
         }