Add a name for the anonymous type we're creating for subrange
types and a FIXME for what we should be doing. Should solve the
immediacy of PR12069 where our debug info is crashing another
tool.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171536 91177308-0d34-0410-b5e6-96231b3b80d8