Reapply "s/grep/FileCheck/ in some tests"

This reverts commit fd1335e982bbf93c5f450ed4fd29f9f787435c85.

Use a triple this time.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175134 91177308-0d34-0410-b5e6-96231b3b80d8