kill get-default run-pass test

It no longer passes, and the ui test subsumes it anyhow.

src/test/run-pass/nll/get_default.rs

@@ -1,31 +0,0 @@
-// Copyright 2016 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.
-
-#![feature(nll)]
-
-use std::collections::HashMap;
-
-fn get_default(map: &mut HashMap<usize, String>, key: usize) -> &mut String {
-    match map.get_mut(&key) {
-        Some(value) => value,
-        None => {
-            map.insert(key, "".to_string());
-            map.get_mut(&key).unwrap()
-        }
-    }
-}
-
-fn main() {
-    let map = &mut HashMap::new();
-    map.insert(22, format!("Hello, world"));
-    map.insert(44, format!("Goodbye, world"));
-    assert_eq!(&*get_default(map, 22), "Hello, world");
-    assert_eq!(&*get_default(map, 66), "");
-}