[clang] [clang] VectorExprEvaluator::VisitCallExpr - add constant folding for X86 pslldqi/psrldqi intrinsics (PR #157403)

[Simon Pilgrim via cfe-commits]

https://github.com/RKSimon requested changes to this pull request.

This still doesn't merge with trunk - please can you resolve

https://github.com/llvm/llvm-project/pull/157403