rustc-ap-rustc_cratesio_shim 421.0.0

Automatically published version of the package `rustc_cratesio_shim` in the rust-lang/rust repository from commit fbd34efb32b9efb574899e4335bdc8c6525ac27e The publishing script for this crate lives at: https://github.com/alexcrichton/rustc-auto-publish