[clang-tools-extra] [clang-doc] Improve performance by adding a short circuit (PR #96809)

[Paul Kirth via cfe-commits]

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

If we can confirm that the only differences in documentation generation are due to ordering, then I think it makes sense to land this patch.

https://github.com/llvm/llvm-project/pull/96809