heimdal: Fix: Too large time skew, client time 1970-01-01T01:00:00

Part of ed549cb0c53f zeroed out a data structure in the resulting code-file
when a TUTCTime type was freed. This part of the patch applies to Heimdal
7.1+ and not our Heimdal 1.5.2.

PR: 267827
Reported by: Peter Much <pmc@citylink.dinoex.sub.org>
Tested by: Peter Much <pmc@citylink.dinoex.sub.org>
Approved by: so
Security: FreeBSD-EN-22:28.heimdal
Fixes: ed549cb0c53f

(cherry picked from commit f556a05c49261af3d373c599d05fa250f3563b59)
(cherry picked from commit 5afe36c8b79547cda2bdd7297e5e2507a9135945)