[jdk13u-dev] RFR: 8260356: (tz) Upgrade time-zone data to tzdata2021a

[Dmitry Cherepanov]

request to backport upgrade to tzdata2021a to 13u. Applies cleanly, relevant tests passed.

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Commit messages:
 - Backport d9aefa36ac1d4b711a3082e3ce6c442d4cb8e718

Changes: https://git.openjdk.java.net/jdk13u-dev/pull/138/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk13u-dev&pr=138&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8260356
  Stats: 12 lines in 3 files changed: 6 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk13u-dev/pull/138.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk13u-dev pull/138/head:pull/138

PR: https://git.openjdk.java.net/jdk13u-dev/pull/138