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

[Shilei Tian via cfe-commits]

shiltian wrote:

I'm not sure if calling it `libomp.a` is a good idea. I personally find it confusing because "libomp" is already an established name—it refers to the OpenMP host runtime contributed by Intel, just as "libgomp" is the OpenMP host runtime for GCC. These names are well-recognized. On the other hand, I have no issue with continuing to call it `libomptarget.devicertl.a`. Other than that, I think this is a great thing to have and a big step forward.

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