remove the Any bound from CrateStore

This is a [breaking-change] for plugins, which
ought by now to have stopped relying on downcasting.

Author: nikomatsakis

src/librustc/middle/cstore.rs

@@ -150,12 +150,7 @@ pub struct ExternCrate {
 
 /// A store of Rust crates, through with their metadata
 /// can be accessed.
-///
-/// The `: Any` bound is a temporary measure that allows access
-/// to the backing `rustc_metadata::cstore::CStore` object. It
-/// will be removed in the near future - if you need to access
-/// internal APIs, please tell us.
-pub trait CrateStore<'tcx> : Any {
+pub trait CrateStore<'tcx> {
     // item info
     fn stability(&self, def: DefId) -> Option<attr::Stability>;
     fn deprecation(&self, def: DefId) -> Option<attr::Deprecation>;