RFR: 8317956: Make jdk.internal.util.Architecture current architecture final

[Roger Riggs]

The static for the current architecture should be final to allow some optimizations.

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Commit messages:
 - 8317956: Make jdk.internal.util.Archecture current architecture final

Changes: https://git.openjdk.org/jdk/pull/16150/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16150&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8317956
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16150.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16150/head:pull/16150

PR: https://git.openjdk.org/jdk/pull/16150