Use wrapping_div call and correct the feature name

Author: mvdnes

src/libcore/num/wrapping.rs

@@ -119,13 +119,13 @@ macro_rules! wrapping_impl {
             }
         }
 
-        #[stable(feature = "rust1", since = "1.3.0")]
+        #[stable(feature = "wrapping_div", since = "1.3.0")]
         impl Div for Wrapping<$t> {
             type Output = Wrapping<$t>;
 
             #[inline(always)]
             fn div(self, other: Wrapping<$t>) -> Wrapping<$t> {
-                Wrapping(self.0 / other.0)
+                Wrapping(self.0.wrapping_div(other.0))
             }
         }