No known invocation of mktime(3c) produces anything other than -1.
Peter A. Bigot
Author: Peter A. Bigot <firstname.lastname@example.org>
Date: Sun Dec 30 14:25:50 2012 -0600
SF 3598947 mktime() fails
Tracked down to use of PCTS, which is the NIST POSIX Compliance Test Suite.
The only remaining vestige of it was to bypass accepting a correct mktime()
result in favor of a complex solution involving normalizing struct tm using
timezones that we don't support.