Pass cfg.SEED to dataloader building

Summary:
Pull Request resolved: https://github.com/facebookresearch/d2go/pull/651

As title, so that dataloading is deterministic when `cfg.SEED` is set.

Reviewed By: navsud

Differential Revision: D53547772

fbshipit-source-id: 73cfd2b351e81b370fb721a4f7b7c2a6313470bd

d2go/data/build.py

@@ -159,7 +159,7 @@ def build_weighted_detection_train_loader(
             )
         )
 
-    sampler = RepeatFactorTrainingSampler(repeat_factors)
+    sampler = RepeatFactorTrainingSampler(repeat_factors, seed=cfg.SEED)
 
     return build_batch_data_loader(
         dataset,
@@ -167,6 +167,7 @@ def build_weighted_detection_train_loader(
         cfg.SOLVER.IMS_PER_BATCH,
         aspect_ratio_grouping=cfg.DATALOADER.ASPECT_RATIO_GROUPING,
         num_workers=cfg.DATALOADER.NUM_WORKERS,
+        seed=cfg.SEED,
     )