[compiler-rt] [compiler-rt] Initial support for builtins on GPU targets (PR #95304)

[Joseph Huber via llvm-commits]

jhuber6 wrote:

@petrhosek I'm trying to get it working through the `LLVM_ENABLE_RUNTIMES` path, but for some reason the `CMAKE_CXX_COMPILER_ID` doesn't seem to be set. It's set for other runtimes builds using the same interface (libc), but not for the separate builtins build. Is there some special handling we do here?

https://github.com/llvm/llvm-project/pull/95304