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

[Saleem Abdulrasool via llvm-commits]

https://github.com/compnerd approved this pull request.

Sure, this seems safe enough as is to merge I think. I wonder if we can push the flags into the cache file, but that isn't a requirement for this I think - we can clean that up subsequently.

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