[jdk13u-dev] RFR: 8242010: Update IANA Language Subtag Registry to Version 2020-04-01

[Yuri Nesterenko]

should be backported for consistency. Applies cleanly; tests do pass.

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Commit messages:
 - Backport 51a5e9ca3ce53ff75be4eb0aed2d55c109cf5094

Changes: https://git.openjdk.java.net/jdk13u-dev/pull/218/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk13u-dev&pr=218&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8242010
  Stats: 296 lines in 5 files changed: 259 ins; 7 del; 30 mod
  Patch: https://git.openjdk.java.net/jdk13u-dev/pull/218.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk13u-dev pull/218/head:pull/218

PR: https://git.openjdk.java.net/jdk13u-dev/pull/218