timezone data: update to 2017b

Update timezone data to 2017b.

http://mm.icann.org/pipermail/tz-announce/2017-February/000045.html
http://mm.icann.org/pipermail/tz-announce/2017-March/000046.html

Key changes in 2017a-2017b:

* Mongolia no longer observes DST.
* Chile's Region of Magallanes moves from -04/-03 to -03 year-round.
* Switch to numeric time zone abbreviations for South America, as
  part of the ongoing project of removing invented abbreviations.
* Haiti resumed observance of DST in 2017.

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