[clang] [clang][x86] Ensure we use the shifted value bit width to check for out of bounds per-element shift amounts (PR #156019)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

I would have expected additional test coverage since this looks like it would change behavior for out of bound shift amounts.

https://github.com/llvm/llvm-project/pull/156019