Problem reported by Paul Wise for Debian, in:
https://bugs.debian.org/851934
This is fallout from the fix for GNU Bug#23035.
* src/date.c (batch_convert): New args TZ and TZSTRING.
All uses changed.
(batch_convert, main): Adjust to parse_datetime2 API change.
(main): Allocate time zone object.
* tests/misc/date-debug.sh: Fix incorrect test case,
caught by the fix.
* tests/misc/date.pl: Test the fix.