Create rustdoc_internals feature gate

Author: GuillaumeGomez

core/src/lib.rs

@@ -165,7 +165,8 @@
 #![feature(decl_macro)]
 #![feature(doc_cfg)]
 #![feature(doc_notable_trait)]
-#![feature(doc_primitive)]
+#![cfg_attr(bootstrap, feature(doc_primitive))]
+#![cfg_attr(not(bootstrap), feature(rustdoc_internals))]
 #![feature(exhaustive_patterns)]
 #![feature(doc_cfg_hide)]
 #![feature(extern_types)]

std/src/lib.rs

@@ -275,10 +275,11 @@
 #![feature(decl_macro)]
 #![feature(doc_cfg)]
 #![feature(doc_cfg_hide)]
-#![feature(doc_keyword)]
+#![cfg_attr(bootstrap, feature(doc_primitive))]
+#![cfg_attr(bootstrap, feature(doc_keyword))]
+#![cfg_attr(not(bootstrap), feature(rustdoc_internals))]
 #![feature(doc_masked)]
 #![feature(doc_notable_trait)]
-#![feature(doc_primitive)]
 #![feature(dropck_eyepatch)]
 #![feature(duration_checked_float)]
 #![feature(duration_constants)]