Replace nodename with ipa_gethostfqdn()
ipa_kdb and ipa-join now use ipa_gethostfqdn() instead of uname()'s nodename.
The code for hostname in ipa-join is simplified. Now the hostname is
auto-detected and verified in main(). All sub functions can now use the
hostname without additional checks. This removes a bunch of strdup(),
NULL checks, and free() calls.
Fixes: https://pagure.io/freeipa/issue/8501
Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Fraser Tweedale <ftweedal@redhat.com>