ac8fc09688
Unset `-march` when invoking the compiler and linker to build the GPU libraries. These libraries use GPU targets rather than the CPU targets, and an incidental `-march=native` causes Clang to be able to determine the GPU used — which causes the build to fail when there is no GPU available. Resetting `-march=` should suffice to revert to building generic code for the time being. See the discussion in: https://github.com/llvm/llvm-project/pull/126143#issuecomment-2816718492