misc: Add missing license and copyrights

This commit adds missing license notices and copyrighs for code written
by @josephlr.

Signed-off-by: Akira Moroo <retrage01@gmail.com>

src/arch/x86_64/asm.rs

@@ -1,3 +1,6 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2020 Google LLC
+
 use core::arch::global_asm;
 
 global_asm!(include_str!("ram32.s"), options(att_syntax, raw));

src/arch/x86_64/gdt.rs

@@ -1,3 +1,6 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2020 Google LLC
+
 use core::mem::size_of;
 
 bitflags::bitflags! {

src/arch/x86_64/paging.rs

@@ -1,3 +1,6 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2020 Google LLC
+
 use x86_64::{
     registers::control::Cr3,
     structures::paging::{PageSize, PageTable, PageTableFlags, PhysFrame, Size2MiB},

src/arch/x86_64/ram32.s

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# Copyright 2020 Google LLC
+
 .section .text32, "ax"
 .global ram32_start
 .code32

src/arch/x86_64/sse.rs

@@ -1,3 +1,6 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2020 Google LLC
+
 use x86_64::registers::control::{Cr0, Cr0Flags, Cr4, Cr4Flags};
 
 // Enable SSE2 for XMM registers (needed for EFI calling)

src/pvh.rs

@@ -1,3 +1,6 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2020 Google LLC
+
 use core::mem::size_of;
 
 use crate::{