[llvm] [gitattributes] Mark some llvm-rc inputs as requiring LF newlines (PR #113222)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

> `tag-html.test` is still failing in CI with this change, so I'd rather take mine

Right, the workers don't do a fresh clone, but only update on top of their existing checkout with faulty newlines...

I'll keep this PR open for now, to keep in mind that we could apply this instead of #113000 once things are sorted out in the CI.

https://github.com/llvm/llvm-project/pull/113222