[llvm] [llvm-rc] Handle Windows line endings in tag-html test (PR #113000)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

> > Are you seeing those issues still if you rebase your branch to a recent base version?
> > See #86318 for the source of those issues - that was reverted in [e669bbb](https://github.com/llvm/llvm-project/commit/e669bbbb7265a7d4d59bac2d3889194efa167ea8). And there's a chance that it can end up reapplied with `.gitattributes` enforcing checking out these files with LF newlines.
> 
> I'm still seeing failures in the CI machines - even with that change reverted, I don't think that it's forcing Git to re-create the files with the correct line endings.
> 
> Just looking through recent PRs with build failures, I see https://buildkite.com/llvm-project/github-pull-requests/builds/111934#0192b0c1-cdad-4ace-936e-93d0626d903d which has the revert in its commit history, but is still failing due to this issue (and the other which I recently merged a fix for).

Ah, right, because it seems that the CI machines only updates the existing workdir, it doesn't do a full new checkout. So it seems like the CI machines have started up right in the window when the problematic gitattributes were in effect, and any attempts to fix it via gitattributes has no effect now. See https://discourse.llvm.org/t/windows-premerge-buildbot-broken-for-5-days/82571/4 for discussion around this as well.

I presume this fix is good enough for now; when we get the workers checkouts flushed and re-checked out with LF newlines again, I'd prefer to go with the solution from #113222, but for now this is probably fine.

https://github.com/llvm/llvm-project/pull/113000