Fix PR19239 - Add support for generating debug info for functions without lexical scopes and/or debug info at all

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204790 91177308-0d34-0410-b5e6-96231b3b80d8
Add tests for r204790

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204791 91177308-0d34-0410-b5e6-96231b3b80d8