the type exists.
Fix up cases where we weren't checking for optional types and add
an assert to addType to make sure we catch this in the future.
Fix up a testcase that was using the tag for DW_TAG_array_type
when it meant DW_TAG_enumeration_type.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187963 91177308-0d34-0410-b5e6-96231b3b80d8