Remove reexport of HeapSizeOf in util (#6419)

ethcore/src/verification/queue/mod.rs

@@ -22,6 +22,7 @@ use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering as AtomicOrdering};
 use std::sync::{Condvar as SCondvar, Mutex as SMutex, Arc};
 use std::cmp;
 use std::collections::{VecDeque, HashSet, HashMap};
+use heapsize::HeapSizeOf;
 use util::*;
 use io::*;
 use error::*;