Upgrade to Rust 1.17.

- Remove some uses of 'static in const and static globals that are no
  longer needed.
- Use the new struct initialization shorthand.

lib/cretonne/src/iterators.rs

@@ -8,10 +8,7 @@ pub trait IteratorExtras: Iterator {
               Self::Item: Clone
     {
         let elem = self.next();
-        AdjacentPairs {
-            iter: self,
-            elem: elem,
-        }
+        AdjacentPairs { iter: self, elem }
     }
 }