Replace const_generics feature gate with min_const_generics

The latter is on the path to stabilization.

Author: est31

compiler/rustc_data_structures/src/lib.rs

@@ -26,7 +26,7 @@
 #![feature(thread_id_value)]
 #![feature(extend_one)]
 #![feature(const_panic)]
-#![feature(const_generics)]
+#![feature(min_const_generics)]
 #![feature(once_cell)]
 #![allow(rustc::default_hash_types)]