Rémy Rakic

All the prerequisite PRs have landed.

My understanding is that test builders use `download-ci-llvm`, which has `llvm.libzstd` enabled by default on x64 linux. The `x86_64-gnu` builder already has `libzstd-dev` installed but it probably shouldn't be needed...

(Let me know what tests and try builds we'd want to double-check.)

[zlib](https://github.com/rust-lang-ci/rust/actions/runs/10333315674/job/28605514096#step:25:48082) > test [run-make] tests/run-make/compressed-debuginfo ... ok [zstd](https://github.com/rust-lang-ci/rust/actions/runs/10333315674/job/28605514096#step:25:48085) > test [run-make] tests/run-make/compressed-debuginfo-zstd ... ok --- I've removed the dependency from the test runner image, let's see what happens now. @bors...

[Cool](https://github.com/rust-lang-ci/rust/actions/runs/10334928775/job/28608909805#step:25:48082), the two tests (that now fail when a compression algorithm isn't found) still pass > test [run-make] tests/run-make/compressed-debuginfo ... ok > test [run-make] tests/run-make/compressed-debuginfo-zstd ... ok

> Could you try to make a fake LLVM change to see what happens? I pushed changes to `rustc_llvm` as it's easier than messing with the llvm submodule. Let's see...

I sure hope switching to another repo won't download LLVM again! @bors try

Alright I pushed a different commit to the llvm fork, hopefully the builder will pick it now .... @bors try

Sure we can install the package on the test builder and enable zstd, but still manually build a specific version on the dist builder? Or should we build-ztsd.sh on both?

This should be the last try to see the tests pass 🤞 @bors try