DebugInfo: Update testcase to actually check something

This test was missing a `Debug Info Version` so it's `not grep` was
passing vacuously.  Update it to CHECK for something useful at the same
time so it doesn't bitrot quite so easily in the future.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224324 91177308-0d34-0410-b5e6-96231b3b80d8