Fix style check for the stable toolchain

Author: qinsoon

src/policy/marksweepspace/malloc_ms/mod.rs

@@ -2,4 +2,3 @@ mod global;
 mod metadata;
 
 pub use global::*;
-pub use metadata::*;

src/util/statistics/mod.rs

@@ -1,4 +1,3 @@
-pub use self::counter::Counter;
 pub use self::counter::Timer;
 
 pub mod counter;