[jdk26u] RFR: 8375657: RISC-V: Need to check size in SharedRuntime::is_wide_vector

[Dingli Zhang]

Hi all,

This pull request contains a backport of commit [ca3e6236](https://github.com/openjdk/jdk/commit/ca3e6236a28794156cc2acf697755229c47735a8) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

The commit being backported was authored by Dingli Zhang on 20 Jan 2026 and was reviewed by Feilong Jiang and Fei Yang.

Thanks!

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Commit messages:
 - Backport ca3e6236a28794156cc2acf697755229c47735a8

Changes: https://git.openjdk.org/jdk26u/pull/20/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk26u&pr=20&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8375657
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk26u/pull/20.diff
  Fetch: git fetch https://git.openjdk.org/jdk26u.git pull/20/head:pull/20

PR: https://git.openjdk.org/jdk26u/pull/20