std: Move platform specific stdio code into sys

src/libstd/io/stdio.rs

@@ -125,13 +125,10 @@ impl<R: io::Read> io::Read for Maybe<R> {
 }
 
 fn handle_ebadf<T>(r: io::Result<T>, default: T) -> io::Result<T> {
-    #[cfg(windows)]
-    const ERR: i32 = ::sys::c::ERROR_INVALID_HANDLE as i32;
-    #[cfg(not(windows))]
-    const ERR: i32 = ::libc::EBADF as i32;
+    use sys::stdio::EBADF_ERR;
 
     match r {
-        Err(ref e) if e.raw_os_error() == Some(ERR) => Ok(default),
+        Err(ref e) if e.raw_os_error() == Some(EBADF_ERR) => Ok(default),
         r => r
     }
 }

src/libstd/sys/unix/stdio.rs

@@ -65,3 +65,5 @@ impl io::Write for Stderr {
     }
     fn flush(&mut self) -> io::Result<()> { Ok(()) }
 }
+
+pub const EBADF_ERR: i32 = ::libc::EBADF as i32;

src/libstd/sys/windows/stdio.rs

@@ -205,3 +205,5 @@ impl Output {
 fn invalid_encoding() -> io::Error {
     io::Error::new(io::ErrorKind::InvalidData, "text was not valid unicode")
 }
+
+pub const EBADF_ERR: i32 = ::sys::c::ERROR_INVALID_HANDLE as i32;