Revert "[X86] Fold shuffle(not(x),undef) -> not(shuffle(x,undef))"

This reverts commit 925093d8.

Causes an infinite loop when compiling some shuffles:

$ cat bugpoint-reduced-simplified.ll
target triple = "x86_64-unknown-linux-gnu"

define void @foo() {
entry:
  %0 = load i8, i8* undef, align 1
  %broadcast.splatinsert = insertelement <16 x i8> poison, i8 %0, i32 0
  %1 = icmp ne <16 x i8> %broadcast.splatinsert, zeroinitializer
  %2 = shufflevector <16 x i1> %1, <16 x i1> undef, <16 x i32> zeroinitializer
  %wide.load = load <16 x i8>, <16 x i8>* undef, align 1
  %3 = icmp ne <16 x i8> %wide.load, zeroinitializer
  %4 = and <16 x i1> %3, %2
  %5 = zext <16 x i1> %4 to <16 x i8>
  store <16 x i8> %5, <16 x i8>* undef, align 1
  ret void
}

$ llc < bugpoint-reduced-simplified.ll
<timeout>