Get rid of CUDA_VISIBLE_DEVICES

It is not clear to me what the purpose of this is, but it has recently
started causing failures.

codes/utils/options.py

@@ -8,11 +8,6 @@ Loader, Dumper = OrderedYaml()
 def parse(opt_path, is_train=True):
     with open(opt_path, mode='r') as f:
         opt = yaml.load(f, Loader=Loader)
-    # export CUDA_VISIBLE_DEVICES
-    if 'gpu_ids' in opt.keys():
-        gpu_list = ','.join(str(x) for x in opt['gpu_ids'])
-        os.environ['CUDA_VISIBLE_DEVICES'] = gpu_list
-        print('export CUDA_VISIBLE_DEVICES=' + gpu_list)
 
     opt['is_train'] = is_train