[llvm] [offload] Extend LIT infrastructure to allow using more tools (PR #124636)

[Nick Sarnie via llvm-commits]

sarnex wrote:

It looks like the file name of the `--save-temps` output will be `a-spirv64-intel-.0.o` for my case, with `a.out` being the final binary output name, so I probably can guess it.

I guess I can add a precompiled object file in the `Inputs` directory, call `clang-linker-wrapper` on it and expect it to fail using `not` since we can't set up the `ld` arguments, and then hardcode a check for `a-spirv64-intel-.0.o` and call the tools I want on that.

This seems like a strange way to do testing, but if you feel this way is better I can do it that way.

https://github.com/llvm/llvm-project/pull/124636