[jdk21u] RFR: 8316743: RISC-V: Change UseVectorizedMismatchIntrinsic option result to warning

[Fei Yang]

VectorizedMismatch intrinsic is not implemented on linux-riscv platform. Backport this fix to avoid JVM crash when user specified JVM options -XX:+UnlockDiagnosticVMOptions -XX:+UseVectorizedMismatchIntrinsic on the command line. RISC-V only change, risk is low.

-------------

Commit messages:
 - Backport 750da0012931656cfd55f3e67c3f49ad7363ab8e

Changes: https://git.openjdk.org/jdk21u/pull/224/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=224&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316743
  Stats: 6 lines in 2 files changed: 5 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk21u/pull/224.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/224/head:pull/224

PR: https://git.openjdk.org/jdk21u/pull/224