flask: remove xen_flask_userlist operation
This operation has no known users, and is primarily useful when an MLS
policy is in use (which has never been shipped with Xen). In addition,
the information it provides does not actually depend on hypervisor
state (only on the XSM policy), so an application that needs it could
compute the results without needing to involve the hypervisor.
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Doug Goldstein <cardoe@cardoe.com>