[vectorIntrinsics] RFR: 8274631: assert(false) failed: bad AD file with -XX:UseKNLSetting

[Jatin Bhateja]

- Fix for assertion failure in test/hotspot/jtreg/compiler/vectorapi/VectorMaskCastTest.java crashes during compilation over KNL target.
- A safety check has been added to prevent intrinsification of VectorMask.cast API if source and destination have incompatible ideal types i.e one is predicate vector type (TypeVectMask) and other a vector type (TypeVect).

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Commit messages:
 - 8274631: assert(false) failed: bad AD file with -XX:UseKNLSetting

Changes: https://git.openjdk.java.net/panama-vector/pull/141/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=141&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274631
  Stats: 8 lines in 1 file changed: 8 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/panama-vector/pull/141.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-vector pull/141/head:pull/141

PR: https://git.openjdk.java.net/panama-vector/pull/141