The zone file parser does not support Tzif3 files

[algernon]

As the title says: the zone file parser does not support tzif3 format files, which is produced by zic >= 2013. This causes test case failures on at least Fedora.

The updated manpage says:

For version-3-format time zone files, the POSIX-TZ-style string may use
two minor extensions to the POSIX TZ format, as described in
newtzset(3).  First, the hours part of its transition times may be
signed and range from -167 through 167 instead of the POSIX-required
unsigned values from 0 through 24.  Second, DST is in effect all year
if it starts January 1 at 00:00 and ends December 31 at 24:00 plus the
difference between daylight saving and standard time.

Originally reported by Peter Czanik czanik@balabit.hu

[algernon]

This will need the following changes:

• Allow version 3 at the top of zone_info_parser()
• Allow gmt_offsets between -167 and 167 in v3 (currently it's 0-24)

As far as I see, we ignore DST anyway, so that part need not be changed.