[jdk8u-dev] RFR: 8339803: Acknowledge case insensitive unambiguous keywords in tzdata files

[Dmitry Cherepanov]

Improves parsing of keywords in tzdata rules

- The patch from 11u doesn't apply cleanly due to [JDK-8042369](https://bugs.openjdk.org/browse/JDK-8042369) missing in 8u. I backported new version of `parseYear` method (https://hg.openjdk.org/jdk9/jdk9/jdk/rev/6c26f18d9bc0#l8.347) with minor adaption to 8u codebase and then replaced uses of `equals()` with `regionMatches()`
- Minor conflict in copyright year in RuleRec.java, applied manually

Testing: all relevant tests passed (java/text/Format java/util/TimeZone sun/util/calendar sun/util/resources)

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Commit messages:
 - Backport 2155f8d22a5e34d9b9386485b2a6a1c2bdf8b52c

Changes: https://git.openjdk.org/jdk8u-dev/pull/632/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=632&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339803
  Stats: 40 lines in 3 files changed: 3 ins; 17 del; 20 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/632.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/632/head:pull/632

PR: https://git.openjdk.org/jdk8u-dev/pull/632