Add some hacks to get stdin piping working more correctly in windows

The way pipes work in windows is not the same as unix, though I'm not
entirely clear on the differences. This patch changes the windows pipe
method to return non-inheritable fds, and the windows rust_run_program
method to duplicate them before spawning the new process.

This allows make-check-pretty to work on windows.

src/test/stdtest/run.rs

@@ -1,5 +1,9 @@
 use std;
 import std::run;
+import std::os;
+import std::io;
+import std::option;
+import std::str;
 
 // Regression test for memory leaks
 #[cfg(target_os = "linux")]
@@ -15,4 +19,49 @@ fn test_leaks() {
 #[cfg(target_os = "win32")]
 #[test]
 #[ignore]
-fn test_leaks() { }
+fn test_leaks() { }
+
+#[test]
+fn test_pipes() {
+    let pipe_in = os::pipe();
+    let pipe_out = os::pipe();
+    let pipe_err = os::pipe();
+
+    let pid = run::spawn_process("cat", [],
+       pipe_in.in, pipe_out.out, pipe_err.out);
+    os::libc::close(pipe_in.in);
+    os::libc::close(pipe_out.out);
+    os::libc::close(pipe_err.out);    
+    
+    if pid == -1 { fail; }
+    let expected = "test";
+    writeclose(pipe_in.out, expected);
+    let actual = readclose(pipe_out.in);
+    readclose(pipe_err.in);
+    os::waitpid(pid);
+    
+    log expected;
+    log actual;
+    assert expected == actual;
+    
+    fn writeclose(fd: int, s: &str) {
+        let writer = io::new_writer(
+            io::fd_buf_writer(fd, option::none));
+        writer.write_str(s);
+
+        os::libc::close(fd);
+    }
+
+    fn readclose(fd: int) -> str {
+        // Copied from run::program_output
+        let file = os::fd_FILE(fd);
+        let reader = io::new_reader(io::FILE_buf_reader(file, option::none));
+        let buf = "";
+        while !reader.eof() {
+            let bytes = reader.read_bytes(4096u);
+            buf += str::unsafe_from_bytes(bytes);
+        }
+        os::libc::fclose(file);
+        ret buf;
+    }
+}