[jdk17u] RFR: 8272413: Incorrect num of element count calculation for vector cast

[Tobias Hartmann]

Backport of [JDK-8272413](https://bugs.openjdk.java.net/browse/JDK-8272413). Applies cleanly. Approval is pending.

Thanks,
Tobias

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Commit messages:
 - 8272413: Incorrect num of element count calculation for vector cast

Changes: https://git.openjdk.java.net/jdk17u/pull/100/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=100&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272413
  Stats: 3 lines in 1 file changed: 0 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/100.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/100/head:pull/100

PR: https://git.openjdk.java.net/jdk17u/pull/100