This adds all CodeGen tests for the SystemZ target.
This version of the patch incorporates feedback from a review by
Sean Silva. Thanks to all reviewers!
Patch by Richard Sandiford.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181204 91177308-0d34-0410-b5e6-96231b3b80d8