[lworld+vector] RFR: 8319971: [lworld+vector] Fallback implementation cleanups.

[Jatin Bhateja]

Some cleanup related to Unsafe APIs based fallback implementation.

Best Regards,
Jatin

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Commit messages:
 - jchecks fix
 - 8319971: [lworld+vector] Fallback implementation cleanups.

Changes: https://git.openjdk.org/valhalla/pull/949/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=949&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319971
  Stats: 895 lines in 39 files changed: 104 ins; 28 del; 763 mod
  Patch: https://git.openjdk.org/valhalla/pull/949.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/949/head:pull/949

PR: https://git.openjdk.org/valhalla/pull/949