rustbuild: Replace create_dir_racy with create_dir_all

`create_dir_all` has since been fixed so no need for `create_dir_racy`.

src/build_helper/lib.rs

@@ -13,7 +13,6 @@
 extern crate filetime;
 
 use std::fs::File;
-use std::io;
 use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
 use std::{fs, env};
@@ -211,7 +210,7 @@ pub fn native_lib_boilerplate(src_name: &str,
 
     let out_dir = env::var_os("RUSTBUILD_NATIVE_DIR").unwrap_or(env::var_os("OUT_DIR").unwrap());
     let out_dir = PathBuf::from(out_dir).join(out_name);
-    t!(create_dir_racy(&out_dir));
+    t!(fs::create_dir_all(&out_dir));
     if link_name.contains('=') {
         println!("cargo:rustc-link-lib={}", link_name);
     } else {
@@ -260,21 +259,3 @@ fn fail(s: &str) -> ! {
     println!("\n\n{}\n\n", s);
     std::process::exit(1);
 }
-
-fn create_dir_racy(path: &Path) -> io::Result<()> {
-    match fs::create_dir(path) {
-        Ok(()) => return Ok(()),
-        Err(ref e) if e.kind() == io::ErrorKind::AlreadyExists => return Ok(()),
-        Err(ref e) if e.kind() == io::ErrorKind::NotFound => {}
-        Err(e) => return Err(e),
-    }
-    match path.parent() {
-        Some(p) => try!(create_dir_racy(p)),
-        None => return Err(io::Error::new(io::ErrorKind::Other, "failed to create whole tree")),
-    }
-    match fs::create_dir(path) {
-        Ok(()) => Ok(()),
-        Err(ref e) if e.kind() == io::ErrorKind::AlreadyExists => Ok(()),
-        Err(e) => Err(e),
-    }
-}