[clang] [Clang][OpenMP] Fix multi arch compilation for -march option (PR #92290)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

I don't think we want to support this. `-march` was the wrong option to use in the first place, and upstream LLVM never supported specifying multiple device images with `-march` so there isn't a legacy argument in trunk. However, AOMP did support this and if it's deemed too disruptive to request users move to `--offload-arch=a,b,c` then we can carry that change in the fork.

> It will fix tests like: [targetid_multi_image](https://github.com/ROCm/aomp/tree/aomp-dev/test/smoke/targetid_multi_image)

I think the easier way to fix this is to update the Makefile.

https://github.com/llvm/llvm-project/pull/92290