native, rustuv: Fix spawning with empty args

There was a bug in both libnative and libuv which prevented child processes from
being spawned correctly on windows when one of the arguments was an empty
string. The libuv bug has since been fixed upstream, and the libnative bug was
fixed as part of this commit.

When updating libuv, this also includes a fix for #15149.

Closes #15149
Closes #16272

src/test/run-pass/issue-15149.rs

@@ -18,9 +18,7 @@ use std::io::{TempDir, Command, fs};
 use std::os;
 use std::task::TaskBuilder;
 
-// FIXME(#15149) libgreen still needs to be update. There is an open PR for it
-//               but it is not yet merged.
-// green_start!(main)
+green_start!(main)
 
 fn main() {
     // If we're the child, make sure we were invoked correctly

src/test/run-pass/issue-16272.rs

@@ -0,0 +1,45 @@
+// Copyright 2014 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(phase)]
+#[phase(plugin)]
+extern crate green;
+extern crate native;
+
+use native::NativeTaskBuilder;
+use std::io::{process, Command};
+use std::os;
+use std::task::TaskBuilder;
+
+green_start!(main)
+
+fn main() {
+    let len = os::args().len();
+
+    if len == 1 {
+        test();
+        let (tx, rx) = channel();
+        TaskBuilder::new().native().spawn(proc() {
+            tx.send(test());
+        });
+        rx.recv();
+    } else {
+        assert_eq!(len, 3);
+    }
+}
+
+fn test() {
+    let status = Command::new(os::self_exe_name().unwrap())
+                         .arg("foo").arg("")
+                         .stdout(process::InheritFd(1))
+                         .stderr(process::InheritFd(2))
+                         .status().unwrap();
+    assert!(status.success());
+}