Adjustments for (upcoming) LLVM-23 and Clang's new offload driver

[linehill]

This patch updates chipStar to work on non-forked, upstream LLVM-23. The recent Clang has switched to use its new offload driver by default for HIP compilation and chipStar is adjusted to it. There is a still an option to use the old while it still around in Clang.

That said, chipStar doesn't yet work on the recent Clang until the following upstream patch lands:
llvm/llvm-project#187655.

[colleeneb]

/run-aurora-ci

[colleeneb]

/run-aurora-ci

[pvelesko]

We already have #1194

This PR is missing CI for llvm 23 @linehill anything wrong with the existing PR?

[linehill]

We already have #1194

This PR is missing CI for llvm 23 @linehill anything wrong with the existing PR?

That one haven't seen progress for a while and its changes are based on an old LLVM revision that wouldn't work on the more recent one.

[pvelesko]

That one haven't seen progress for a while and its changes are based on an old LLVM revision that wouldn't work on the more recent one.

Yeah I got it to the stage where things were working but since LLMV is still getting commits in I didn't see the point in doing further work until LLVM side PRs are merged.

[linehill]

Yeah I got it to the stage where things were working but since LLMV is still getting commits in I didn't see the point in doing further work until LLVM side PRs are merged.

Fair enough. We (PoCL) have a goal to have the chipStar working on non-forked Clang before the LLVM-23 release. Given your on-going LLVM upstream efforts (MacOS and SPIR-V BE support for HIPSPV and maybe more?), I'm concerned if we are going to miss that set goal if we need to wait them to be merged first.