Make sure all resource states have at least one subresource state

* Even if it's invalid, this removes the need to check whether the data
  for a given id is empty or not.

renderdoc/driver/d3d12/d3d12_replay.cpp

@@ -1443,6 +1443,9 @@ void D3D12Replay::SavePipelineState()
       for(size_t l = 0; l < it->second.size(); l++)
         res.states[l].name = ToStr(it->second[l]);
 
+      if(res.states.empty())
+        res.states.push_back({"Unknown"});
+
       i++;
     }
   }

renderdoc/driver/vulkan/vk_replay.cpp

@@ -1452,6 +1452,12 @@ void VulkanReplay::SavePipelineState()
         img.layouts[l].numMip = it->second.subresourceStates[l].subresourceRange.levelCount;
       }
 
+      if(img.layouts.empty())
+      {
+        img.layouts.push_back(VKPipe::ImageLayout());
+        img.layouts[0].name = "Unknown";
+      }
+
       i++;
     }
   }