rust: zerocopy-derive: add SPDX License Identifiers

Originally, when the Rust upstream `alloc` standard library crate was
vendored, the SPDX License Identifiers were added to every file so that
the license on those was clear. The same happened with the vendoring of
`proc_macro2`, `quote` and `syn`. Please see:

  commit 057b8d2571 ("rust: adapt `alloc` crate to the kernel")
  commit 69942c0a89 ("rust: syn: add SPDX License Identifiers")
  commit ddfa1b279d ("rust: quote: add SPDX License Identifiers")
  commit a9acfceb96 ("rust: proc-macro2: add SPDX License Identifiers")

Thus do the same for the `zerocopy-derive` crate.

This makes `scripts/spdxcheck.py` pass: use parentheses like commit
06e9bfc1e5 ("ionic: make spdxcheck.py happy") did since we have two
`OR` operators in the expression (three licenses).

Finally, as requested, I filed an issue [1] with upstream about it.

Cc: Joshua Liebow-Feeser <joshlf@google.com>
Cc: Jack Wrenn <jswrenn@google.com>
Link: https://github.com/google/zerocopy/issues/3428 [1]
Link: https://patch.msgid.link/20260608141439.182634-15-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

rust/zerocopy-derive/derive/from_bytes.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT
+
 use proc_macro2::{Span, TokenStream};
 use syn::{
     parse_quote, Data, DataEnum, DataStruct, DataUnion, Error, Expr, ExprLit, ExprUnary, Lit, UnOp,

rust/zerocopy-derive/derive/into_bytes.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT
+
 use proc_macro2::{Span, TokenStream};
 use quote::quote;
 use syn::{Data, DataEnum, DataStruct, DataUnion, Error, Type};

rust/zerocopy-derive/derive/known_layout.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT
+
 use proc_macro2::TokenStream;
 use quote::quote;
 use syn::{parse_quote, Data, Error, Type};

rust/zerocopy-derive/derive/mod.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT
+
 pub mod from_bytes;
 pub mod into_bytes;
 pub mod known_layout;

rust/zerocopy-derive/derive/try_from_bytes.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT
+
 use proc_macro2::TokenStream;
 use quote::quote;
 use syn::{

rust/zerocopy-derive/derive/unaligned.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT
+
 use proc_macro2::{Span, TokenStream};
 use syn::{Data, DataEnum, DataStruct, DataUnion, Error};
 

rust/zerocopy-derive/lib.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT
+
 // Copyright 2019 The Fuchsia Authors
 //
 // Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0

rust/zerocopy-derive/repr.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT
+
 // Copyright 2019 The Fuchsia Authors
 //
 // Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0

rust/zerocopy-derive/util.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: (BSD-2-Clause OR Apache-2.0) OR MIT
+
 // Copyright 2019 The Fuchsia Authors
 //
 // Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0