Add diagnostic translation lints to crates that don't emit them

compiler/rustc_traits/src/lib.rs

@@ -1,6 +1,8 @@
 //! New recursive solver modeled on Chalk's recursive solver. Most of
 //! the guts are broken up into modules; see the comments in those modules.
 
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 #![feature(let_else)]
 #![recursion_limit = "256"]