exec: Include missing license in 'exec/cpu-common.h'

Commit 1ad2134f91 ("Hardware convenience library") extracted
"cpu-common.h" from "cpu-all.h", which uses the LGPL-2.1+ license.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20240427155714.53669-5-philmd@linaro.org>
diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index 6d53188..8812ba7 100644
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -1,8 +1,13 @@
+/*
+ * CPU interfaces that are target independent.
+ *
+ *  Copyright (c) 2003 Fabrice Bellard
+ *
+ * SPDX-License-Identifier: LGPL-2.1+
+ */
 #ifndef CPU_COMMON_H
 #define CPU_COMMON_H
 
-/* CPU interfaces that are target independent.  */
-
 #include "exec/vaddr.h"
 #ifndef CONFIG_USER_ONLY
 #include "exec/hwaddr.h"