[X86][SSE] Canonicalize UNARYSHUFFLE(XOR(X,-1) -> XOR(UNARYSHUFFLE(X),-1)

This pushes the NOT pattern up the DAG to help expose it for further combines (AND->ANDN in particular).

The PSHUFD/MOVDDUP 'splat' cases are the only ones I've seen in the wild so far, we can further generalize if/when we need to.