Use assert_eq! rather than assert!

The previous code was passing "true" as the panic! error value.

src/libstd/num/mod.rs

@@ -1633,7 +1633,7 @@ mod tests {
                 assert_eq!((3 as $T).is_power_of_two(), false);
                 assert_eq!((4 as $T).is_power_of_two(), true);
                 assert_eq!((5 as $T).is_power_of_two(), false);
-                assert!(($T::MAX / 2 + 1).is_power_of_two(), true);
+                assert_eq!(($T::MAX / 2 + 1).is_power_of_two(), true);
             }
         )
     }