remove stabilized feature flag

Author: RalfJung

src/bin/miri-rustc-tests.rs

@@ -1,4 +1,4 @@
-#![feature(rustc_private, extern_crate_item_prelude)]
+#![feature(rustc_private)]
 extern crate miri;
 extern crate getopts;
 extern crate rustc;

src/bin/miri.rs

@@ -1,4 +1,4 @@
-#![feature(rustc_private, extern_crate_item_prelude)]
+#![feature(rustc_private)]
 
 extern crate getopts;
 extern crate miri;

src/lib.rs

@@ -1,4 +1,4 @@
-#![feature(rustc_private, extern_crate_item_prelude)]
+#![feature(rustc_private)]
 
 #![cfg_attr(feature = "cargo-clippy", allow(cast_lossless))]
 

tests/run-pass-fullmir/foreign-fn-linkname.rs

@@ -10,7 +10,7 @@
 
 //ignore-windows: Uses POSIX APIs
 
-#![feature(libc, extern_crate_item_prelude)]
+#![feature(libc)]
 #![allow(unused_extern_crates)] // rustc bug https://github.com/rust-lang/rust/issues/56098
 
 extern crate libc;