Remove unused features from rustc_middle.

Author: nnethercote

compiler/rustc_middle/src/lib.rs

@@ -35,9 +35,9 @@
 #![feature(const_type_name)]
 #![feature(discriminant_kind)]
 #![feature(coroutines)]
-#![feature(stmt_expr_attributes)]
 #![feature(if_let_guard)]
 #![cfg_attr(bootstrap, feature(inline_const))]
+#![feature(intra_doc_features)]
 #![feature(iter_from_coroutine)]
 #![feature(negative_impls)]
 #![feature(never_type)]
@@ -50,12 +50,10 @@
 #![feature(strict_provenance)]
 #![cfg_attr(bootstrap, feature(associated_type_bounds))]
 #![feature(rustc_attrs)]
-#![feature(control_flow_enum)]
 #![feature(trait_upcasting)]
 #![feature(try_blocks)]
 #![feature(decl_macro)]
 #![feature(extract_if)]
-#![feature(intra_doc_pointers)]
 #![feature(yeet_expr)]
 #![feature(const_option)]
 #![feature(ptr_alignment_type)]