qemu-keymap: Add license in generated files

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Message-Id: <20211117174533.1900570-1-philmd@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
diff --git a/qemu-keymap.c b/qemu-keymap.c
index 536e8f2..4095b65 100644
--- a/qemu-keymap.c
+++ b/qemu-keymap.c
@@ -187,6 +187,7 @@
     }
 
     fprintf(outfile,
+            "# SPDX-License-Identifier: GPL-2.0-or-later\n"
             "#\n"
             "# generated by qemu-keymap\n"
             "#    model   : %s\n"