[llvm] [Runtimes] Prevent builtins from clobbering runtimes configuration (PR #185664)

[Saleem Abdulrasool via llvm-commits]

https://github.com/compnerd commented:

I'm sorry, I don't know about this option and cannot find any documentation or mention of it in the CMake codebase. Can you please point me to where this is documented?

https://github.com/llvm/llvm-project/pull/185664