memberof: Do not create request with 0 attribute values
    
    [sysdb_set_entry_attr] (0x0080): ldb_modify failed: [Constraint violation](19)
      [attribute 'ghost': attribute on 'name=Escalation,cn=groups,cn=LDAP,cn=sysdb'
      specified, but with 0 values (illegal)]
    [sysdb_error_to_errno] (0x0020): LDB returned unexpected error:
      [Constraint violation]
    [sysdb_set_entry_attr] (0x0040): Error: 14 (Bad address)
    [sdap_store_group_with_gid] (0x0040): Could not store group Escalation
    [sdap_save_group] (0x0080): Could not store group with GID: [Bad address]
    [sdap_save_group] (0x0080): Failed to save group [Escalation]: [Bad address]
    [sdap_save_groups] (0x0040): Failed to store group 1. Ignoring.
    
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
    (cherry picked from commit 999c87114479f230c840a5c020e107c45b29fd56)