[x86] Teach the new vector shuffle lowering to also use pmovzx for v4i32
shuffles that are zext-ing.

Not a lot to see here; the undef lane variant is better handled with
pshufd, but this improves the actual zext pattern.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218112 91177308-0d34-0410-b5e6-96231b3b80d8