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

[Simon Pilgrim via cfe-commits]

RKSimon wrote:

@kimyounhoex1 I've merged trunk latest into this patch so that the byteshift builtins now use vXi8 types - #158671

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