uucore/buf_copy: add copyright notice

Author: DaringCuteSeal

src/uucore/src/lib/features/buf_copy/common.rs

@@ -1,3 +1,8 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
 use crate::error::UError;
 
 /// Error types used by buffer-copying functions from the `buf_copy` module.

src/uucore/src/lib/features/buf_copy/linux.rs

@@ -1,3 +1,8 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
 use nix::sys::stat::fstat;
 use nix::{errno::Errno, libc::S_IFIFO};
 

src/uucore/src/lib/features/buf_copy/other.rs

@@ -1,3 +1,8 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
 use std::io::{Read, Write};
 
 use crate::error::UResult;