[DebugInfo/Verifier] Don't emit error for missing module in index

We don't expect module names to be present in the index. This patch adds
DW_TAG_module to the blacklist.

Differential revision: https://reviews.llvm.org/D50237

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338878 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed