vsock: add SPDX-License-Identifier in each file

Harsha specified `license = "Apache-2.0 OR BSD-3-Clause"` in
vsock/Cargo.toml, so let's add a properly SPDX tag in the
vsock files.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>

vsock/src/main.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 or BSD-3-Clause
+
 mod rxops;
 mod rxqueue;
 mod thread_backend;

vsock/src/rxops.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 or BSD-3-Clause
+
 #[derive(Clone, Copy, Eq, PartialEq, Debug)]
 pub enum RxOps {
     /// VSOCK_OP_REQUEST

vsock/src/rxqueue.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 or BSD-3-Clause
+
 use super::rxops::RxOps;
 
 #[derive(Debug, Eq, PartialEq)]

vsock/src/thread_backend.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 or BSD-3-Clause
+
 #![deny(missing_docs)]
 
 use super::{

vsock/src/txbuf.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 or BSD-3-Clause
+
 use super::vhu_vsock::{Error, Result, CONN_TX_BUF_SIZE};
 use std::{io::Write, num::Wrapping};
 use vm_memory::{bitmap::BitmapSlice, VolatileSlice};

vsock/src/vhu_vsock.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 or BSD-3-Clause
+
 use super::vhu_vsock_thread::*;
 use clap::Parser;
 use core::slice;

vsock/src/vhu_vsock_thread.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 or BSD-3-Clause
+
 use super::{
     rxops::*,
     thread_backend::*,

vsock/src/vsock_conn.rs

@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0 or BSD-3-Clause
+
 use super::{
     rxops::*,
     rxqueue::*,