Made unit tests more reliable

dlib/test/dnn.cpp

@@ -2143,7 +2143,7 @@ namespace
         trainer.set_learning_rate(1e-5);
         trainer.set_min_learning_rate(1e-11);
         trainer.set_mini_batch_size(50);
-        trainer.set_max_num_epochs(300);
+        trainer.set_max_num_epochs(2000);
         trainer.train(x, y);
 
         running_stats<double> rs;
@@ -2228,6 +2228,8 @@ namespace
     {
         print_spinner();
 
+        srand(1234);
+
         const int output_width = 7;
         const int output_height = 7;
         const int num_samples = 100;