Cleanup: skip unnecessary OIIO image setup when not using tiled render

intern/cycles/session/tile.cpp

@@ -367,6 +367,7 @@ void TileManager::update(const BufferParams &params, const Scene *scene)
 
   buffer_params_ = params;
 
+  if (has_multiple_tiles()) {
     /* TODO(sergey): Proper Error handling, so that if configuration has failed we don't attempt to
      * write to a partially configured file. */
     configure_image_spec_from_buffer(&write_state_.image_spec, buffer_params_, tile_size_);
@@ -383,6 +384,11 @@ void TileManager::update(const BufferParams &params, const Scene *scene)
     else {
       overscan_ = 0;
     }
+  }
+  else {
+    write_state_.image_spec = ImageSpec();
+    overscan_ = 0;
+  }
 }
 
 bool TileManager::done()