RFR: 8336844: ZipConstants64 defines duplicate constants ZIP64_EXTID and EXTID_ZIP64

Fri Jul 19 19:39:58 UTC 2024

This change deduplicates constants in ZipConstants64 for the Zip64 Extended Information Extra Field Header ID (see APPNOTE.TXT 4.5.3).

I think there are arguments for consolidating on either `EXTID_ZIP64` or `ZIP64_EXTID`. The PR currently consolidates on `EXTID_ZIP64`, `ZIP64_EXTID` is also an option if there's a preference for that.

I noticed this while working on a zip64 bug in [JDK-8328995](https://bugs.openjdk.org/browse/JDK-8328995), I was reviewing places that handled zip64 extra fields and initially missed some because I was only looking at one of the constants.

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Commit messages:
 - 8336844: ZipConstants64 defines duplicate constants EXTID_ZIP64 and EXTID_ZIP64.

Changes: https://git.openjdk.org/jdk/pull/20264/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20264&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336844
  Stats: 10 lines in 6 files changed: 0 ins; 2 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/20264.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20264/head:pull/20264

PR: https://git.openjdk.org/jdk/pull/20264