configure: cross compile should use x86_64 cpu_family

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Joelle van Dyne <j@getutm.app>
Message-id: 20210126012457.39046-9-j@getutm.app
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
1 file changed