`x install` fails because bootstrap can't copy files from the llvm-project submodule

This goes back to:
https://github.com/rust-lang/rust/issues/140913

Specifically:
https://github.com/rust-lang/rust/issues/140913#issuecomment-2898357101

The fix did not work for me due to build issues. Could this be an incomplete fix?