Fixed global_function_search's initialization being wrong if explicitly

given an empty list of initial function evaluations.

dlib/global_optimization/global_function_search.cpp

@@ -629,7 +629,7 @@ namespace dlib
         {
             functions[i]->ub = upper_bound_function(initial_function_evals[i], relative_noise_magnitude);
 
-            if (initial_function_evals.size() != 0)
+            if (initial_function_evals[i].size() != 0)
             {
                 auto best = max_scoring_element(initial_function_evals[i], [](const function_evaluation& e) { return e.y; }).first;
                 functions[i]->best_objective_value = best.y;