[Updated] tzcode 2020a

[Brian Inglis]

The following packages have been updated in the Cygwin distribution:

* tzcode 2020a

The Time Zone Database (often called tz, tzdb, or zoneinfo) contains
data that represents the history of local time for many locations
around the world.
It is updated periodically to reflect changes made by political bodies
to daylight saving (summer time) rules, UTC offsets, and time zone
boundaries.

News for the tz database

Release 2020a - 2020-04-23 16:03:47 -0700

  Briefly:
    zic now supports expiration dates for leap second lists.

For more information, see the announcement or below:

https://mm.icann.org/pipermail/tz-announce/2020-April/000058.html

Changes to code

    localtime.c no longer mishandles timestamps after the last
    transition in a TZif file with leap seconds and with daylight
    saving time transitions projected into the indefinite future.
    For example, with TZ='America/Los_Angeles' with leap seconds,
    zdump formerly reported a DST transition on 2038-03-14
    from 01:59:32.999... to 02:59:33 instead of the correct transition
    from 01:59:59.999... to 03:00:00.

    zic -L now supports an Expires line in the leapseconds file, and
    truncates the TZif output accordingly.  This propagates leap
    second expiration information into the TZif file, and avoids the
    abovementioned localtime.c bug as well as similar bugs present in
    many client implementations.  If no Expires line is present, zic
    -L instead truncates the TZif output based on the #expires comment
    present in leapseconds files distributed by tzdb 2018f and later;
    however, this usage is obsolescent.  For now, the distributed
    leapseconds file has an Expires line that is commented out, so
    that the file can be fed to older versions of zic which ignore the
    commented-out line.  Future tzdb distributions are planned to
    contain a leapseconds file with an Expires line.

    The configuration macros HAVE_TZNAME and USG_COMPAT should now be
    set to 1 if the system library supports the feature, and 2 if not.
    As before, these macros are nonzero if tzcode should support the
    feature, zero otherwise.

    The configuration macro ALTZONE now has the same values with the
    same meaning as HAVE_TZNAME and USG_COMPAT.

    The code's defense against CRLF in leap-seconds.list is now
    portable to POSIX awk.  (Problem reported by Deborah Goldsmith.)

    Although the undocumented tzsetwall function is not changed in
    this release, it is now deprecated in preparation for removal in
    future releases.  Due to POSIX requirements, tzsetwall has not
    worked for some time.  Any code that uses it should instead use
    tzalloc(NULL) or, if portability trumps thread-safety, should
    unset the TZ environment variable.