[MS Demangler] Anonymous namespace hashes can be backreferenced.

Previously we were not remembering the key values of anonymous
namespaces, but we need to do this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@340238 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed