RFR: 8288979: Improve CLDRConverter run time [v3]

[Daniel Jeliński]

> This PR improves the performance of deduplication done by ResourceBundleGenerator.
> 
> The original implementation compared every pair of values, requiring O(n^2) time. The new implementation uses a HashMap to find duplicates, trading off some extra memory consumption for O(n) computational complexity. In practice the time to generate jdk.localedata on my Linux VM files dropped from 14 to 8 seconds.
> 
> The resulting files (under build/support/gensrc/java.base and jdk.localedata) have different contents; map iteration order depends on the insertion order, and the insertion order of the new implementation is different from the original.
> The files generated before and after this change have the same size.

Daniel Jeliński has updated the pull request incrementally with one additional commit since the last revision:

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9243/files
  - new: https://git.openjdk.org/jdk/pull/9243/files/6cb47724..8d26e537

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9243&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9243&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9243.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9243/head:pull/9243

PR: https://git.openjdk.org/jdk/pull/9243