Remove features array_from_fn, alloc_layout_extra

Summary: Not used.

Reviewed By: bobyangyf

Differential Revision: D40893544

fbshipit-source-id: c181ce80aa7413a5d84b4366b1ba7f1812fef0d0

Author: stepancheg

starlark/src/lib.rs

@@ -347,7 +347,6 @@
 
 // Features we use
 #![allow(stable_features)]
-#![feature(alloc_layout_extra)]
 #![feature(bench_black_box)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
@@ -363,7 +362,6 @@
 #![feature(maybe_uninit_write_slice)]
 #![feature(ptr_metadata)]
 #![feature(thread_local)]
-#![feature(array_from_fn)]
 // Plugins
 #![cfg_attr(feature = "gazebo_lint", feature(plugin))]
 #![cfg_attr(feature = "gazebo_lint", allow(deprecated))] // :(