[clang] [Clang] Fix null pointer dereference in enum debug info generation (PR #105556)

[Tom Honermann via cfe-commits]

https://github.com/tahonermann approved this pull request.

Per discussion in https://github.com/llvm/llvm-project/pull/97105, this looks good to me.

However, please do update the PR title and adjust the commit message accordingly when merging the change as requested by @pogo59.

https://github.com/llvm/llvm-project/pull/105556