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

[Saleem Abdulrasool via llvm-commits]

compnerd 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.

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