acl: Fix X support in ACL permissions

If you try to set rwX permissions, ACL fails to set them at all.

Expected:

    $ sudo setfacl -m 'group::rwX' www
    ...
    drwxrwxr-x  2 root root  4096 Nov 10 17:09 www

With Ansible:

    acl: name=/var/www permissions=rwX etype=group state=present
    ...
    drwxrw-r-x  2 root root  4096 Nov 10 17:30 www

x for group is erased. =/