typecheckWholeCoreBindings: misleading variable name `prepd_binding`

GHC.IfaceToCore.typecheckWholeCoreBindings is defined with the following pattern match:

typecheckWholeCoreBindings type_var (WholeCoreBindings prepd_binding this_mod _) =
  ...

This made me hopeful that I can store Prep'd bindings in fat interface files, which is exactly what I'd like (I don't want to re-Prep them after loading, and there are also some Prep post-processing that I could persist in fat interface files). Alas, it doesn't work out because it doesn't solve the Prep shadowing problem. So that variable should be renamed to tidy_bindings, and it should be documented what exactly is to be put in the fat ModIfaces.