Revert alloc_system change
diff --git a/libc-test/tests/all.rs b/libc-test/tests/all.rs
index 15d3181..42a743c 100644
--- a/libc-test/tests/all.rs
+++ b/libc-test/tests/all.rs
@@ -1,7 +1,5 @@
-#![feature(alloc_system)]
 #![allow(bad_style, unused_imports)]
 
-extern crate alloc_system;
 extern crate libc;
 extern crate libc_test;