This option hasn't done anything for a long time, and can be
removed. I've kept a shim in place to avoid breaking docs.rs,
but the option no longer does anything.
Using git-blame, I tracked this option down to
f77ebd4ffa, the commit that
introduced EmitType in the first place. It was used with
SharedResource::Unversioned, which no longer exists since
f9e1f6ffdf removed them.
CC https://github.com/rust-lang/rust/pull/146220
Part of https://github.com/rust-lang/rust/issues/83784
fe3490c562