Import tzdata 2018i

Changes: https://github.com/eggert/tz/blob/2018i/NEWS

MFC after:	2 days

contrib/tzdata/NEWS

@@ -1,5 +1,17 @@
 News for the tz database
 
+Release 2018i - 2018-12-30 11:05:43 -0800
+
+  Briefly:
+    São Tomé and Príncipe switches from +01 to +00 on 2019-01-01.
+
+  Changes to future timestamps
+
+    Due to a change in government, São Tomé and Príncipe switches back
+    from +01 to +00 on 2019-01-01 at 02:00.  (Thanks to Vadim
+    Nasardinov and Michael Deckers.)
+
+
 Release 2018h - 2018-12-23 17:59:32 -0800
 
   Briefly:

contrib/tzdata/africa

@@ -1144,10 +1144,20 @@ Zone	Indian/Reunion	3:41:52 -	LMT	1911 Jun # Saint-Denis
 # the switch is from 01:00 to 02:00 ... [Decree No. 25/2017]
 # http://www.mnec.gov.st/index.php/publicacoes/documentos/file/90-decreto-lei-n-25-2017
 
+# From Vadim Nasardinov (2018-12-29):
+# São Tomé and Príncipe is about to do the following on Jan 1, 2019:
+# https://www.stp-press.st/2018/12/05/governo-jesus-ja-decidiu-repor-hora-legal-sao-tomense/
+#
+# From Michael Deckers (2018-12-30):
+# https://www.legis-palop.org/download.jsp?idFile=102818
+# ... [The legal time of the country, which coincides with universal
+# coordinated time, will be restituted at 2 o'clock on day 1 of January, 2019.]
+
 Zone	Africa/Sao_Tome	 0:26:56 -	LMT	1884
 			-0:36:45 -	LMT	1912 Jan  1 00:00u # Lisbon MT
 			 0:00	-	GMT	2018 Jan  1 01:00
-			 1:00	-	WAT
+			 1:00	-	WAT	2019 Jan  1 02:00
+			 0:00	-	GMT
 
 # Senegal
 # See Africa/Abidjan.

contrib/tzdata/version

@@ -1 +1 @@
-2018h
+2018i