fix bugs for data_loading_tutorial and dcgan_faces_tutorial (#1092)

Author: guyang3532

beginner_source/data_loading_tutorial.py

@@ -374,7 +374,7 @@ def __call__(self, sample):
 #
 
 dataloader = DataLoader(transformed_dataset, batch_size=4,
-                        shuffle=True, num_workers=4)
+                        shuffle=True, num_workers=0)
 
 
 # Helper function to show a batch

beginner_source/dcgan_faces_tutorial.py

@@ -591,7 +591,7 @@ def forward(self, input):
         # Format batch
         real_cpu = data[0].to(device)
         b_size = real_cpu.size(0)
-        label = torch.full((b_size,), real_label, device=device)
+        label = torch.full((b_size,), real_label, dtype=torch.float, device=device)
         # Forward pass real batch through D
         output = netD(real_cpu).view(-1)
         # Calculate loss on all-real batch