configure: allow disable of cross compilation containers

configure: allow disable of cross compilation containers

Our docker infrastructure isn't quite as multiarch as we would wish so
lets allow the user to disable it if they want. This will allow us to
use still run check-tcg on non-x86 CI setups.

Signed-off-by: Alex Bennée <[email protected]>
Reviewed-by: Stefan Weil <[email protected]>
Reviewed-by: Cleber Rosa <[email protected]>
Tested-by: Cleber Rosa <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Tested-by: Richard Henderson <[email protected]>