Remove unused X86andn_flag node.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189654 91177308-0d34-0410-b5e6-96231b3b80d8
Fixup BZHI selection to remove an unneeded zero extension.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189656 91177308-0d34-0410-b5e6-96231b3b80d8