[libclc] [libclc] use default paths with find_program when possible (PR #105969)

[Tristan Ross via cfe-commits]

RossComputerGuy wrote:

> Apologies, but I'm having a bit of trouble understanding the scenario that this PR addresses.

Nixpkgs adds the tools being used to `$PATH` so find program needs to use path.

https://github.com/llvm/llvm-project/pull/105969