<i18n dev> RFR: 6560981: (cal) unused local variables in GregorianCalendar, etc.

[Justin Lu]

Problem: Unused variables in GregorianCalendar, JapaneseImperialCalendar, and Base Calendar.

Fix: Removed all unused variables in bug description except normalizedYear in JapaneseImpericalCalendar.getActualMaximum.() as there was no matching unused variable within that method.

Additionally removed realDayOfYear in GregorianCalendar.computeFields.() due to redundancy.

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Commit messages:
 - Update copyright
 - Remove unusued/redundant code

Changes: https://git.openjdk.org/jdk/pull/10585/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10585&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-6560981
  Stats: 9 lines in 3 files changed: 0 ins; 6 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/10585.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10585/head:pull/10585

PR: https://git.openjdk.org/jdk/pull/10585