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

[Matt Arsenault via llvm-commits]

arsenm wrote:

> Making the backend rely on it is difficult because of (2), but agreed.
> 
> >

Not for compiler-rt, we can just assume it's version locked. The resource problem is also simpler for compiler-rt. We can more easily just define a fixed register budget, and then just assume there's no stack usage 

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