Omit standard copyright notice

Remove copyright notices for files licensed under the standard terms (MIT OR Apache-2.0).

Author: xtqqczze

example/alloc_system.rs

@@ -1,6 +1,3 @@
-// SPDX-License-Identifier: MIT OR Apache-2.0
-// SPDX-FileCopyrightText: The Rust Project Developers (see https://thanks.rust-lang.org)
-
 #![no_std]
 #![feature(allocator_api, rustc_private)]