timezone data: update to 2018d

timezone data: update to 2018d

Update timezone data to 2018d
http://mm.icann.org/pipermail/tz-announce/2018-March/000049.html
  In 2018, Palestine starts DST on March 24, not March 31.
     Adjust future predictions accordingly.
  Casey Station in Antarctica changed from +11 to +08
(cherry picked from commit c7369830b62b69b9537ec68f6bfe193e11963164)

timezone data: update to 2018c
Update timezone data to 2018c
http://mm.icann.org/pipermail/tz-announce/2018-January/000048.html
   Briefly:
   Sao Tome and Príncipe switched from +00 to +01.
   Brazil's DST will now start on November's first Sunday.
(cherry picked from commit eae2f37b62393b0355238507ffdddb045b7d2fdb)

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.
(cherry picked from commit ede51e4641b1053e214d294e06a935e0b2bcf09a)

luci-base: add Etc/GMT timezones
Add Etc/GMT timezones like GMT+5
(cherry picked from commit f2cf516cf7d50c191e3ea94f4696a6c60348cf92)

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