Add copyright check file (rust-lang#7)

Add file for copyright checks based on the upstream version of the same
file. This way we keep the format for the library folder.

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.reuse/dep5

@@ -0,0 +1,26 @@
+# WARNING: this metadata is currently incomplete, do not rely on it yet.
+
+Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
+
+Files: library/*
+Copyright: The Rust Project Developers (see https://thanks.rust-lang.org)
+License: MIT or Apache-2.0
+
+Files: library/core/src/unicode/unicode_data.rs
+Copyright: 1991-2022 Unicode, Inc. All rights reserved.
+License: Unicode-DFS-2016
+
+Files: library/std/src/sync/mpmc/*
+Copyright: 2019 The Crossbeam Project Developers
+           The Rust Project Developers (see https://thanks.rust-lang.org)
+License: MIT OR Apache-2.0
+
+Files: library/std/src/sys/sync/mutex/fuchsia.rs
+Copyright: 2016 The Fuchsia Authors
+           The Rust Project Developers (see https://thanks.rust-lang.org)
+License: BSD-2-Clause AND (MIT OR Apache-2.0)
+
+Files: library/backtrace/*
+Copyright: 2014 Alex Crichton
+           The Rust Project Developers (see https://thanks.rust-lang.org)
+License: MIT OR Apache-2.0