fix build issue due to stabilized feature

the8472 · the8472 · commit 08567712483a · 2020-09-03T20:59:23.000+02:00
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
@@ -107,6 +107,7 @@
 #![feature(map_first_last)]
 #![feature(map_into_keys_values)]
 #![feature(negative_impls)]
+#![cfg_attr(bootstrap, feature(never_type))]
 #![feature(new_uninit)]
 #![feature(nll)]
 #![feature(nonnull_slice_from_raw_parts)]
