No src/librustc_llvm as sais in dev guide

On here https://rustc-dev-guide.rust-lang.org/compiler-src.html it says

> One final thing: src/llvm-project is a submodule for our fork of LLVM. During bootstrapping, LLVM is built and the src/librustc_llvm and src/rustllvm crates contain rust wrappers around LLVM (which is written in C++), so that the compiler can interface with it.

but there is no `src/librustc_llvm`