std: more windows fixes to os.rs and run.rs

src/libstd/os.rs

@@ -640,7 +640,7 @@ fn mkdir(p: &Path, _mode: c_int) -> bool {
             use os::win32::as_utf16_p;
             // FIXME: turn mode into something useful? #2623
             do as_utf16_p(p.to_str()) |buf| {
-                libc::CreateDirectoryW(buf, ptr::null() as LPCWSTR)
+                libc::CreateDirectoryW(buf, ptr::mut_null())
                     != (0 as libc::BOOL)
             }
         }
@@ -1080,8 +1080,8 @@ fn FormatMessageA(flags: DWORD,
 
         let mut buf = [0 as c_char, ..TMPBUF_SZ];
 
-        do buf.as_mut_buf |buf, len| {
-            unsafe {
+        unsafe {
+            do buf.as_mut_buf |buf, len| {
                 let res = FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM |
                                          FORMAT_MESSAGE_IGNORE_INSERTS,
                                          ptr::mut_null(),
@@ -1093,7 +1093,9 @@ fn FormatMessageA(flags: DWORD,
                 if res == 0 {
                     fail!("[%?] FormatMessage failure", errno());
                 }
+            }
 
+            do buf.as_imm_buf |buf, _len| {
                 str::raw::from_c_str(buf)
             }
         }

src/libstd/run.rs

@@ -25,7 +25,6 @@
 use ptr;
 use task;
 use vec::ImmutableVector;
-use vec;
 
 /**
  * A value representing a child process.
@@ -691,6 +690,8 @@ mod rustrt {
 
 #[cfg(unix)]
 fn with_argv<T>(prog: &str, args: &[~str], cb: &fn(**libc::c_char) -> T) -> T {
+    use vec;
+
     // We can't directly convert `str`s into `*char`s, as someone needs to hold
     // a reference to the intermediary byte buffers. So first build an array to
     // hold all the ~[u8] byte strings.
@@ -717,6 +718,8 @@ fn with_argv<T>(prog: &str, args: &[~str], cb: &fn(**libc::c_char) -> T) -> T {
 
 #[cfg(unix)]
 fn with_envp<T>(env: Option<&[(~str, ~str)]>, cb: &fn(*c_void) -> T) -> T {
+    use vec;
+
     // On posixy systems we can pass a char** for envp, which is a
     // null-terminated array of "k=v\n" strings. Like `with_argv`, we have to
     // have a temporary buffer to hold the intermediary `~[u8]` byte strings.