[jdk13u-dev] RFR: 8254177: (tz) Upgrade time-zone data to tzdata2020b

[Yuri Nesterenko]

We should catch up timezone data advance: this is tzdata2020b. The patch had one conflict with GendataTZDB.gmk renaming (and no content conflicts there) and a conflict in a test amounted to one symbol change. All relevant regtests do pass AFAIS

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Commit messages:
 - Backport 9c9349098ac2f1f797cdf8490e2eefccb95ecde2

Changes: https://git.openjdk.java.net/jdk13u-dev/pull/42/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk13u-dev&pr=42&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254177
  Stats: 480 lines in 27 files changed: 138 ins; 133 del; 209 mod
  Patch: https://git.openjdk.java.net/jdk13u-dev/pull/42.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk13u-dev pull/42/head:pull/42

PR: https://git.openjdk.java.net/jdk13u-dev/pull/42