Update debug info test for schema change made to LLVM.

This accounts for the addition of another field to DIScopes that will be used
to store a list of DIImportedModules in the future.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178100 91177308-0d34-0410-b5e6-96231b3b80d8