Bump download-ci-llvm-stamp for loong support

[jyn514]

This was missed in #96971 and resulted in the LLVM we cache in CI being different from the one built locally. We didn't catch it because nothing tested the loong support.

Fixes #110474.

r? @nikic

[nikic]

@bors r+ rollup

[bors]

📌 Commit 6787925 has been approved by nikic

It is now in the queue for this repository.

[jyn514]

lol, I actually found this bug a week ago but didn't realize what was going on:

rust/src/bootstrap/dist.rs

Lines 1968 to 1980 in f795a15

	// FIXME: for reasons I don't understand, the LLVM so in the `rustc` component is different than the one in `rust-dev`.
	// Only the one in `rustc` works with the downloaded compiler.
	if builder.download_rustc() && target == builder.build.build {
	let src_libdir = builder.ci_rustc_dir(target).join("lib");
	for entry in t!(std::fs::read_dir(&src_libdir)) {
	let entry = t!(entry);
	if entry.file_name().to_str().unwrap().starts_with("libLLVM-") {
	install_llvm_file(builder, &entry.path(), dst_libdir);
	return !builder.config.dry_run();
	}
	}
	panic!("libLLVM.so not found in src_libdir {}!", src_libdir.display());
	}

I think we can remove that hack after this is merged :) or I can do it now, I'm just not able to test until after the artifacts are uploaded.