[X86][AVX] Push sign extensions of comparison bool results through bitops (PR42025)

[X86][AVX] Push sign extensions of comparison bool results through bitops (PR42025)

As discussed on PR42025, with more complex boolean math we can end up with many truncations/extensions of the comparison results through each bitop.

This patch handles the cases introduced in combineBitcastvxi1 by pushing the sign extension through the AND/OR/XOR ops so its just the original SETCC ops that gets extended.

Differential Revision: https://reviews.llvm.org/D68226

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@373834 91177308-0d34-0410-b5e6-96231b3b80d8