[InstCombine][X86] simplifyX86immShift - handle variable out-of-range vector...

[InstCombine][X86] simplifyX86immShift - handle variable out-of-range vector shift by immediate amounts (PR40391)

If we know the SSE shift amount is out of range then we can simplify to zero value (logical) or a 'signsplat' bitwidth-1 shift (arithmetic). This allows us to remove the equivalent ConstantInt constant folding path from simplifyX86immShift.