Pull up the following revisions, requested by kre in tickt #1589:

external/public-domain/tz/dist/ziguard.awk      up to 1.1.1.1
external/public-domain/tz/dist/CONTRIBUTING    up to 1.1.1.5
external/public-domain/tz/dist/Makefile        up to 1.1.1.20
external/public-domain/tz/dist/NEWS            up to 1.1.1.21
external/public-domain/tz/dist/README          up to 1.1.1.6
external/public-domain/tz/dist/TZDATA_VERSION  up to 1.11
external/public-domain/tz/dist/africa          up to 1.1.1.14
external/public-domain/tz/dist/antarctica      up to 1.1.1.10
external/public-domain/tz/dist/asia            up to 1.1.1.19
external/public-domain/tz/dist/australasia      up to 1.1.1.14
external/public-domain/tz/dist/backzone        up to 1.1.1.14
external/public-domain/tz/dist/checktab.awk    up to 1.1.1.9
external/public-domain/tz/dist/europe          up to 1.1.1.20
external/public-domain/tz/dist/leap-seconds.list up to 1.1.1.9
external/public-domain/tz/dist/leapseconds      up to 1.1.1.10
external/public-domain/tz/dist/northamerica    up to 1.1.1.19
external/public-domain/tz/dist/southamerica    up to 1.1.1.14
external/public-domain/tz/dist/theory.html      up to 1.1.1.3
external/public-domain/tz/dist/version          up to 1.1.1.8
external/public-domain/tz/dist/zishrink.awk    up to 1.1.1.3
external/public-domain/tz/dist/zone.tab        up to 1.1.1.14
external/public-domain/tz/dist/zone1970.tab    up to 1.1.1.16

Update of /cvsroot/src/external/public-domain/tz/dist
In directory ivanova.netbsd.org:/tmp/cvs-serv18468

Log Message:
Import tzdata2018d from ftp://ftp.iana.org/tz/releases/tzdata2018d.tar.gz

Summary of changes in tzdata2018d (2018-03-22 07:05:46 -0700):

        In 2018, Palestine starts DST on March 24 (today!), not March 31

        Casey Station in Antarctica changed from +11 to +08 on 2018-03-11
        at 04:00.

        Various adjustments to some historical conversions (several for
        Uruguay (1920 .. 1990), one fpr Enderbury and Kiritimati (1994/5),
        one for Portugal and colonies (1912) and Jamaica and Turks & Caicos
        (pre 1913)).

(martin)