[x86] Clean up a bunch of vector shuffle tests with my script. Notably,
removes windows line endings and other noise. This is in prelude to
making substantive changes to these tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221776 91177308-0d34-0410-b5e6-96231b3b80d8
[x86] Start improving the matching of unpck instructions based on test
cases from Halide folks. This initial step was extracted from
a prototype change by Clay Wood to try and address regressions found
with Halide and the new vector shuffle lowering.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221779 91177308-0d34-0410-b5e6-96231b3b80d8