[llvm] [LLVM] Silence compiler-rt warning in runtimes build (PR #99525)

[Joseph Huber via llvm-commits]

jhuber6 wrote:

> ```
>   if (LLVM_CONFIG_PATH AND NOT LLVM_CMAKE_DIR)
>     message(WARNING
>       "LLVM_CONFIG_PATH is deprecated, please use LLVM_CMAKE_DIR instead")
> ```
> 
> It seems that they do interact, with `LLVM_CMAKE_DIR` taking precedence, which sounds good to me.

Alright, thanks for the fast review.

While you're here, I need to get the `compiler-rt` tests running on the GPU before I can say it's "supported". One problem is that we don't actually create any tests when compiling the builtins through the `LLVM_ENABLE_RUNTIMES=` approach. This is because we include the `compiler-rt/lib/builtins` CMake directly. I think we will need to add some logic to configure the builtin tests even when done standalone, which would be step 1.

The next step would be adding logic for executing the tests under an "emulator", i.e. `amdhsa-loader a.out` in my case, as well as adding some minimal code to provide the "_start" function on the GPU (this is in `libc` but I don't want  the dependency). I think the `libcxx` project has https://discord.com/channels/636084430946959380/636732535434510338/1263520163290943631 which takes `%{exe}` as an optional argument. Any thoughts?

https://github.com/llvm/llvm-project/pull/99525