Remove unstable features from rustc_errors

Author: nrc

src/Cargo.lock

@@ -11,3 +11,4 @@ crate-type = ["dylib"]
 [dependencies]
 serialize = { path = "../libserialize" }
 syntax_pos = { path = "../libsyntax_pos" }
+libc = "0.2"

src/librustc_errors/Cargo.toml

@@ -1200,8 +1200,12 @@ fn num_overlap(a_start: usize, a_end: usize, b_start: usize, b_end:usize, inclus
     } else {
         0
     };
-    (b_start..b_end + extra).contains(a_start) ||
-    (a_start..a_end + extra).contains(b_start)
+    return range_contains(b_start..b_end + extra, a_start) ||
+           range_contains(a_start..a_end + extra, b_start);
+
+    fn range_contains<T: PartialOrd>(range: ::std::ops::Range<T>, item: T) -> bool {
+        (range.start <= item) && (item < range.end)
+    }
 }
 fn overlaps(a1: &Annotation, a2: &Annotation, padding: usize) -> bool {
     num_overlap(a1.start_col, a1.end_col + padding, a2.start_col, a2.end_col, false)

src/librustc_errors/emitter.rs

@@ -17,12 +17,9 @@
       html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![deny(warnings)]
 
-#![feature(custom_attribute)]
 #![allow(unused_attributes)]
 #![feature(rustc_private)]
 #![feature(staged_api)]
-#![feature(range_contains)]
-#![feature(libc)]
 
 extern crate term;
 extern crate libc;