ZIm/crates/eval/examples/libdevice_symbol_reexport/prompt.md

I'd like to improve the modularity and encapsulation of the NVVM codegen setup. Please refactor the code to reexport LIBDEVICE_BITCODE from the nvvm crate instead of accessing it directly from cust_raw::nvvm_sys. This involves updating the nvvm crate to publicly reexport the symbol, and then modifying rustc_codegen_nvvm to use the reexported path. Additionally, remove the direct dependency on cust_raw from rustc_codegen_nvvm/Cargo.toml and clean up any redundant use statements that reference cust_raw directly. The goal is to simplify usage of nvvm_sys internals by encapsulating them within nvvm, making the codebase more maintainable without changing its behavior.