Warning during compilation about llvm-config --prefix

[hug-dev]

During compilation we observe the following warning:

warning: couldn't execute `llvm-config --prefix` (error: No such file or directory (os error 2))
warning: set the LLVM_CONFIG_PATH environment variable to a valid `llvm-config` executable

This is coming from bindgen crate and its dependency, clang-sys.
clang-sys searches for libclang library on the system using different means and one of them is via executing llvm-config --prefix.
Even if the libclang library is found on the system, a warning will be emitted.

[hug-dev]

Just keeping this issue for reference.