NSS: Move memcache setup to separate function
Related:
https://pagure.io/SSSD/sssd/issue/3496
Reviewed-by: Sumit Bose <sbose@redhat.com>
Reviewed-by: Pavel Březina <pbrezina@redhat.com>
Reviewed-by: Fabiano Fidêncio <fidencio@redhat.com>
Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>