We are not currently running a --disable-tcg test for arm64,
like we are for mips, ppc and s390x.  We have a job for the
native aarch64 runner, but it is not run by default and it
is not helpful for normal developer testing without access
to qemu's private runner.

Use --without-default-features to eliminate most tests.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>