Attempt to fix dragonegg for the removal of DW_TAG_return_variable.

Nothing was conditional upon it in the backend previously and it shouldn't
be necessary, move it to auto variable instead.


git-svn-id: https://llvm.org/svn/llvm-project/dragonegg/trunk@171950 91177308-0d34-0410-b5e6-96231b3b80d8