Update Time Zone Data for ZoneParser

Note: This is usually done as a part of full time zone data update process.

1. Download and unpack the latest version of the TZDB from the IANA Time Zone Database page
   • mkdir tzdata && wget -qO- https://data.iana.org/time-zones/tzdata-latest.tar.gz | tar -xzf - -C tzdata
2. Generate the “rearguard” version of the TZDB
   • CLDR display names assume positive daylight saving offsets. The “rearguard” version is designed for tools without negative daylight saving time support.
   • make -C tzdata rearguard.zi
3. Copy rearguard.zi, version and zone.tab to tools/cldr-code/src/main/resources/org/unicode/cldr/util/data/tzdb
   • cp tzdata/{rearguard.zi,version,zone.tab} tools/cldr-code/src/main/resources/org/unicode/cldr/util/data/tzdb
4. Clean up the working directory
   • rm -r tzdata
5. Record the version: See Updating External Metadata