RFR: 8324048: (fc) Make FileKey fields final [v2]

[Brian Burkhalter]

> Replace use of IDs to set FileKey fields from native with passing down an array, at the expense of an array allocation.

Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:

  8324048: Add and reinstate IOUtil.load(); change long to jlong

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20429/files
  - new: https://git.openjdk.org/jdk/pull/20429/files/0c5f4603..378d7006

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20429&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20429&range=00-01

  Stats: 9 lines in 3 files changed: 8 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/20429.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20429/head:pull/20429

PR: https://git.openjdk.org/jdk/pull/20429