Merge from rustc

Author: RalfJung

src/lib.rs

@@ -273,6 +273,9 @@
     html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
     test(attr(allow(unused_variables), deny(warnings)))
 )]
+#![cfg_attr(not(bootstrap), feature(rustdoc_internals))]
+#![cfg_attr(not(bootstrap), doc(rust_logo))]
+#![cfg_attr(not(bootstrap), allow(internal_features))]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]