PR20038: DebugInfo missing DIEs for some concrete variables.

I haven't nailed this down entirely, but this is about as small of a
test case as I can seem to construct and adequately demonstrates the
crasher. I'll continue investigating the root cause/fix(es).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210993 91177308-0d34-0410-b5e6-96231b3b80d8