[clang] [llvm] [OpenMP] Remove 'libomptarget.devicertl.a' fatbinary and use static library (PR #126143)

[Joseph Huber via llvm-commits]

jhuber6 wrote:

> Nah, building standalone directly. And separately from OpenMP.

I see, it previously worked because when you built with `gcc` it was still finding `clang` in your environment and using that. I'm going to move this code so that it's more explicit that we only support a just-built clang. So, you'd do a separate standalone build where you set the target triple to be the GPU.

https://github.com/llvm/llvm-project/pull/126143