DebugInfo: Update testcases with invalid variables

Fix testcases whose variables are invalid.  I'm working on a patch that
adds `Verifier` checks for `MDLocalVariable` (and `MDGlobalVariable`),
and these failed because:

  - `scope:` fields need to point at `MDLocalScope` and can't be null.
  - `file:` fields need to point at `MDFile`.
  - `inlinedAt:` fields need to point at `MDLocation`.

llvm-svn: 233349