timezone data: update to 2017c

Update timezone data to 2017c

http://mm.icann.org/pipermail/tz-announce/2017-October/000047.html

   Briefly:
   Northern Cyprus switches from +03 to +02/+03 on 2017-10-29.
   Fiji ends DST 2018-01-14, not 2018-01-21.
   Namibia switches from +01/+02 to +02 on 2018-04-01.
   Sudan switches from +03 to +02 on 2017-11-01.
   Tonga likely switches from +13/+14 to +13 on 2017-11-05.
   Turks & Caicos switches from -04 to -05/-04 on 2018-11-04.

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>