RFR: 8271589: fatal error with variable shift count integer rotate operation.

[Jatin Bhateja]

Problem seen on targets which do not support variable vector shifts, in such a case vector rotation node inferred by auto-vectorizer are not disintegrable into LeftShift/RightShift and Or operations.

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Commit messages:
 - 8271589: fatal error with variable shift count integer rotate operation.

Changes: https://git.openjdk.java.net/jdk/pull/4956/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4956&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271589
  Stats: 103 lines in 3 files changed: 92 ins; 1 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4956.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4956/head:pull/4956

PR: https://git.openjdk.java.net/jdk/pull/4956