fix cycle gan cudnn algorithm bug, test=develop (#2474)

PaddleCV/gan/cycle_gan/train.py

@@ -9,12 +9,18 @@ def set_paddle_flags(flags):
         if os.environ.get(key, None) is None:
             os.environ[key] = str(value)
 
+use_cudnn_deterministic = os.environ.get('FLAGS_cudnn_deterministic', None)
+
+if use_cudnn_deterministic:
+    use_cudnn_exhaustive_search = 0
+else:
+    use_cudnn_exhaustive_search = 1
 
 # NOTE(paddle-dev): All of these flags should be
 # set before `import paddle`. Otherwise, it would
 # not take any effect. 
 set_paddle_flags({
-    'FLAGS_cudnn_exhaustive_search': 1,
+    'FLAGS_cudnn_exhaustive_search': use_cudnn_exhaustive_search,
     'FLAGS_conv_workspace_size_limit': 256,
     'FLAGS_eager_delete_tensor_gb': 0, # enable gc 
     # You can omit the following settings, because the default