add #![feature(convert_id)] to libstd + libcore

Author: Centril

src/libcore/lib.rs

@@ -72,6 +72,7 @@
 #![feature(cfg_target_has_atomic)]
 #![feature(concat_idents)]
 #![feature(const_fn)]
+#![feature(convert_id)]
 #![feature(custom_attribute)]
 #![feature(fundamental)]
 #![feature(i128_type)]

src/libstd/lib.rs

@@ -256,6 +256,7 @@
 #![feature(collections_range)]
 #![feature(compiler_builtins_lib)]
 #![feature(const_fn)]
+#![feature(convert_id)]
 #![feature(core_float)]
 #![feature(core_intrinsics)]
 #![feature(dropck_eyepatch)]