Update to tzdata version 2017c.

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

data/CONTRIBUTING

@@ -5,20 +5,26 @@ change timekeeping rules erratically and sometimes with little
 warning, the data entries do not cover all of civil time before
 1970, and undoubtedly errors remain in the code and data.  Feel
 free to fill gaps or fix mistakes, and please email improvements
-to [email protected] for use in the future.
+to [email protected] for use in the future.  In your email, please give
+reliable sources that reviewers can check.
+
+-----
+
+Developers can contribute technical changes to the source code and
+data as follows.
 
 To email small changes, please run a POSIX shell command like
 'diff -u old/europe new/europe >myfix.patch', and attach
 myfix.patch to the email.
 
-For more-elaborate changes, please read the Theory file and browse
-the mailing list archives <http://mm.icann.org/pipermail/tz/> for
-examples of patches that tend to work well.  Ideally, additions to
+For more-elaborate changes, please read the theory.html file and browse
+the mailing list archives <https://mm.icann.org/pipermail/tz/> for
+examples of patches that tend to work well.  Additions to
 data should contain commentary citing reliable sources as
-justification.
+justification.  Citations should use https: URLs if available.
 
 Please submit changes against either the latest release in
-<ftp://ftp.iana.org/tz/> or the master branch of the development
+<https://www.iana.org/time-zones> or the master branch of the development
 repository.  If you use Git the following workflow may be helpful:
 
   * Copy the development repository.

data/LICENSE

@@ -1,4 +1,5 @@
-With a few exceptions, all files in the tz code and data (including
-this one) are in the public domain.  The exceptions are date.c,
-newstrftime.3, and strftime.c, which contain material derived from BSD
-and which use the BSD 3-clause license.
+Unless specified below, all files in the tz code and data (including
+this LICENSE file) are in the public domain.
+
+If the files date.c, newstrftime.3, and strftime.c are present, they
+contain material derived from BSD and use the BSD 3-clause license.

data/NEWS

@@ -1,5 +1,169 @@
 News for the tz database
 
+Release 2017c - 2017-10-20 14:49:34 -0700
+
+  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.
+  A new file tzdata.zi now holds a small text copy of all data.
+  The zic input format has been regularized slightly.
+
+  Changes to future time stamps
+
+    Northern Cyprus has decided to resume EU rules starting
+    2017-10-29, thus reinstituting winter time.
+
+    Fiji ends DST 2018-01-14 instead of the 2018-01-21 previously
+    predicted.  (Thanks to Dominic Fok.)  Adjust future predictions
+    accordingly.
+
+    Namibia will switch from +01 with DST to +02 all year on
+    2017-09-03 at 02:00.  This affects UT offsets starting 2018-04-01
+    at 02:00.  (Thanks to Steffen Thorsen.)
+
+    Sudan will switch from +03 to +02 on 2017-11-01.  (Thanks to Ahmed
+    Atyya and Yahia Abdalla.)  South Sudan is not switching, so
+    Africa/Juba is no longer a link to Africa/Khartoum.
+
+    Tonga has likely ended its experiment with DST, and will not
+    adjust its clocks on 2017-11-05.  Although Tonga has not announced
+    whether it will continue to observe DST, the IATA is assuming that
+    it will not.  (Thanks to David Wade.)
+
+    Turks & Caicos will switch from -04 all year to -05 with US DST on
+    2018-03-11 at 03:00.  This affects UT offsets starting 2018-11-04
+    at 02:00.  (Thanks to Steffen Thorsen.)
+
+  Changes to past time stamps
+
+    Namibia switched from +02 to +01 on 1994-03-21, not 1994-04-03.
+    (Thanks to Arthur David Olson.)
+
+    Detroit did not observe DST in 1967.
+
+    Use railway time for Asia/Kolkata before 1941, by switching to
+    Madras local time (UT +052110) in 1870, then to IST (UT +0530) in
+    1906.  Also, treat 1941-2's +0630 as DST, like 1942-5.
+
+    Europe/Dublin's 1946 and 1947 fallback transitions occurred at
+    02:00 standard time, not 02:00 DST.  (Thanks to Michael Deckers.)
+
+    Pacific/Apia and Pacific/Pago_Pago switched from Antipodean to
+    American time in 1892, not 1879.  (Thanks to Michael Deckers.)
+
+    Adjust the 1867 transition in Alaska to better reflect the
+    historical record, by changing it to occur on 1867-10-18 at 15:30
+    Sitka time rather than at the start of 1867-10-17 local time.
+    Although strictly speaking this is accurate only for Sitka,
+    the rest of Alaska's blanks need to be filled in somehow.
+
+    Fix off-by-one errors in UT offsets for Adak and Nome before 1867.
+    (Thanks to Michael Deckers.)
+
+    Add 7 s to the UT offset in Asia/Yangon before 1920.
+
+  Changes to zone names
+
+    Remove Canada/East-Saskatchewan from the 'backward' file, as it
+    exceeded the 14-character limit and was an unused misnomer anyway.
+
+  Changes to build procedure
+
+    To support applications that prefer to read time zone data in text
+    form, two zic input files tzdata.zi and leapseconds are now
+    installed by default.  The commands 'zic tzdata.zi' and 'zic -L
+    leapseconds tzdata.zi' can reproduce the tzdata binary files
+    without and with leap seconds, respectively.  To prevent these two
+    new files from being installed, use 'make TZDATA_TEXT=', and to
+    suppress leap seconds from the tzdata text installation, use 'make
+    TZDATA_TEXT=tzdata.zi'.
+
+    'make BACKWARD=' now suppresses backward-compatibility names
+    like 'US/Pacific' that are defined in the 'backward' and
+    'pacificnew' files.
+
+    'make check' now works on systems that lack a UTF-8 locale,
+    or that lack the nsgmls program.  Set UTF8_LOCALE to configure
+    the name of a UTF-8 locale, if you have one.
+
+    Y2K runtime checks are no longer enabled by default.  Add
+    -DDEPRECATE_TWO_DIGIT_YEARS to CFLAGS to enable them, instead of
+    adding -DNO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
+    to disable them.  (New name suggested by Brian Inglis.)
+
+    The build procedure for zdump now works on AIX 7.1.
+    (Problem reported by Kees Dekker.)
+
+  Changes to code
+
+    zic and the reference runtime now reject multiple leap seconds
+    within 28 days of each other, or leap seconds before the Epoch.
+    As a result, support for double leap seconds, which was
+    obsolescent and undocumented, has been removed.  Double leap
+    seconds were an error in the C89 standard; they have never existed
+    in civil timekeeping.  (Thanks to Robert Elz and Bradley White for
+    noticing glitches in the code that uncovered this problem.)
+
+    zic now warns about use of the obsolescent and undocumented -y
+    option, and about use of the obsolescent TYPE field of Rule lines.
+
+    zic now allows unambiguous abbreviations like "Sa" and "Su" for
+    weekdays; formerly it rejected them due to a bug.  Conversely, zic
+    no longer considers non-prefixes to be abbreviations; for example,
+    it no longer accepts "lF" as an abbreviation for "lastFriday".
+    Also, zic warns about the undocumented usage with a "last-"
+    prefix, e.g., "last-Fri".
+
+    Similarly, zic now accepts the unambiguous abbreviation "L" for
+    "Link" in ordinary context and for "Leap" in leap-second context.
+    Conversely, zic no longer accepts non-prefixes such as "La" as
+    abbreviations for words like "Leap".
+
+    zic no longer accepts leap second lines in ordinary input, or
+    ordinary lines in leap second input.  Formerly, zic sometimes
+    warned about this undocumented usage and handled it incorrectly.
+
+    The new macro HAVE_TZNAME governs whether the tzname external
+    variable is exported, instead of USG_COMPAT.  USG_COMPAT now
+    governs only the external variables "timezone" and "daylight".
+    This change is needed because the three variables are not in the
+    same category: although POSIX requires tzname, it specifies the
+    other two variables as optional.  Also, USG_COMPAT is now 1 or 0:
+    if not defined, the code attempts to guess it from other macros.
+
+    localtime.c and difftime.c no longer require stdio.h, and .c files
+    other than zic.c no longer require sys/wait.h.
+
+    zdump.c no longer assumes snprintf.  (Reported by Jonathan Leffler.)
+
+    Calculation of time_t extrema works around a bug in GCC 4.8.4
+    (Reported by Stan Shebs and Joseph Myers.)
+
+    zic.c no longer mistranslates formats of line numbers in non-English
+    locales.  (Problem reported by Benno Schulenberg.)
+
+    Several minor changes have been made to the code to make it a
+    bit easier to port to MS-Windows and Solaris.  (Thanks to Kees
+    Dekker for reporting the problems.)
+
+  Changes to documentation and commentary
+
+    The two new files 'theory.html' and 'calendars' contain the
+    contents of the removed file 'Theory'.  The goal is to document
+    tzdb theory more accessibly.
+
+    The zic man page now documents abbreviation rules.
+
+    tz-link.htm now covers how to apply tzdata changes to clients.
+    (Thanks to Jorge Fábregas for the AIX link.)  It also mentions MySQL.
+
+    The leap-seconds.list URL has been updated to something that is
+    more reliable for tzdb.  (Thanks to Tim Parenti and Brian Inglis.)
+
 Release 2017b - 2017-03-17 07:30:38 -0700
 
   Briefly: Haiti has resumed DST.
@@ -15,6 +179,16 @@ Release 2017b - 2017-03-17 07:30:38 -0700
     Use "MMT" to abbreviate Liberia's time zone before 1972, as "-004430"
     is one byte over the POSIX limit.  (Problem reported by Derick Rethans.)
 
+  Changes to code
+
+    The reference localtime implementation now falls back on the
+    current US daylight-saving transition rules rather than the
+    1987-2006 rules.  This fallback occurs only when (1) the TZ
+    environment variable's value has a name like "AST4ADT" that asks
+    for daylight saving time but does not specify the rules, (2) there
+    is no file by that name, and (3) the TZDEFRULES file cannot be
+    loaded.  (Thanks to Tom Lane.)
+
 
 Release 2017a - 2017-02-28 00:05:36 -0800
 
@@ -1981,7 +2155,7 @@ Release 2013e - 2013-09-19 23:50:04 -0700
 
     The 'leapseconds' file is now generated automatically from a
     new file 'leap-seconds.list', which is a copy of
-    <ftp://time.nist.gov/pub/leap-seconds.list>.
+    <ftp://ftp.nist.gov/pub/time/leap-seconds.list>
     A new source file 'leapseconds.awk' implements this.
     The goal is simplification of the future maintenance of 'leapseconds'.
 
@@ -2187,7 +2361,7 @@ Release 2013a - 2013-02-27 09:20:35 -0800
 
   Many changes affect historical timestamps before 1940.
   These were deduced from: Milne J. Civil time. Geogr J. 1899
-  Feb;13(2):173-94 <http://www.jstor.org/stable/1774359>.
+  Feb;13(2):173-94 <https://www.jstor.org/stable/1774359>.
 
   Changes affecting the code:
 

data/SOURCE

@@ -1,2 +1,2 @@
 The files in this directory were obtained from the IANA Time Zone Database
-http://www.iana.org/time-zones, version 2017b.
+http://www.iana.org/time-zones, version 2017c.