docker: remove debian8-mxe definitions

We don't have a debian8-mxe dockerfile anymore.

Fixes: 67bd36beda1ae
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190923181140.7235-2-jsnow@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
1 file changed