Use emplace_back() instead of push_back()

Author: Owen Jones

src/pointer-analysis/local_value_set.cpp

@@ -344,7 +344,7 @@ void local_value_sett::assign(
       {
         external_value_set_exprt evs_non_initializer(
           to_external_value_set(objexpr).as_non_initializer());
-        replacements.push_back({obj.first, evs_non_initializer});
+        replacements.emplace_back(obj.first, evs_non_initializer);
       }
     }