Const correctness in WNEvalPlan::dump()

Enclave/OblivAlgs/WaksmanNetwork.hpp

@@ -101,7 +101,7 @@ struct WNEvalPlan {
     count_switches(Nright);
   }
 
-  void dump(int indent = 0) {
+  void dump(int indent = 0) const {
       printf("%*sN = %lu, nthreads = %lu, inswitches = %lu, outswitches = %lu\n",
           indent, "", N, nthreads, subtree_num_inswitches,
           subtree_num_outswitches);