auto merge of #5206 : thestinger/rust/cmp, r=brson

minor little performance issue - the vector and string implementations of TotalOrd turn out badly without explicitly inlining this

Author: bors

src/libcore/cmp.rs

@@ -45,6 +45,7 @@ pub trait TotalOrd {
     pure fn cmp(&self, other: &Self) -> Ordering;
 }
 
+#[inline(always)]
 pure fn icmp<T: Ord>(a: &T, b: &T) -> Ordering {
     if *a < *b { Less }
     else if *a > *b { Greater }