Title: #797: TESTS: fixed regression in cmocka/test_negcache_2.c
Fixed regression in test introduced in 2b564f8 (PR 786)
Test was relying on hardcoded values of non local users and groups.
Test was changed to find those in runtime.
To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/797/head:pr797
git checkout pr797