Files using serial_hd() should include 'system/system.h'. Fix that.
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250901064631.530723-3-clg@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>