PerfTest: take tree creation into account when timing load

Tests/noDist/PerfTest/TestDriver.hpp

@@ -360,9 +360,9 @@ namespace scalfmm  {
                 algo_factory algo_f;
 
                 // Build tree and load it
+                timers["load"].tic();
                 auto loader = loader_f.build(params);
                 auto tree   = tree_f.build(params, *loader);
-                timers["load"].tic();
                 loader->load(*tree);
                 timers["load"].tac();